Add documentation for syntax nodes and their children

SwiftSyntax’s nodes are currently mostly lacking any documentation. It would be a great community effort to add a description to to every node and every child. Writing documentation for some nodes and children will be easier than for other. The expectation is that if there are any non-obvious things to point out, the documentation should do so. I am happy to help if the semantics of a node or a child are not clear.

To make sure we don’t have multiple PRs adding documentation for the same node please add a comment to this issue with the node(s) you are working on. If you have commit access to this repository, you can also assign a node modify the issue and assign a node to yourself by marking it as ticked and adding your name behind it.

https://github.com/apple/swift-syntax/pull/1527 contains an example of how the documentation of a syntax node could look like.

- [ ] `AccessorBlockSyntax`
- [ ] `AccessorDeclSyntax`
- [ ] `AccessorEffectSpecifiersSyntax`
- [ ] `AccessorParameterSyntax`
- [ ] `AccessPathComponentSyntax`
- [ ] `ActorDeclSyntax`
- [ ] `ArrayElementSyntax`
- [ ] `ArrayExprSyntax`
- [ ] `ArrayTypeSyntax`
- [ ] `ArrowExprSyntax`
- [ ] `AsExprSyntax`
- [ ] `AssignmentExprSyntax`
- [x] `AssociatedtypeDeclSyntax` @whiteio
- [ ] `AttributedTypeSyntax`
- [ ] `AttributeSyntax`
- [ ] `AvailabilityArgumentSyntax`
- [ ] `AvailabilityConditionSyntax`
- [ ] `AvailabilityEntrySyntax`
- [ ] `AvailabilityLabeledArgumentSyntax`
- [ ] `AvailabilityVersionRestrictionListEntrySyntax`
- [ ] `AvailabilityVersionRestrictionSyntax`
- [ ] `AwaitExprSyntax`
- [ ] `BackDeployedAttributeSpecListSyntax`
- [ ] `BinaryOperatorExprSyntax`
- [ ] `BooleanLiteralExprSyntax`
- [ ] `BorrowExprSyntax`
- [ ] `BreakStmtSyntax`
- [ ] `CaseItemSyntax`
- [ ] `CatchClauseSyntax`
- [ ] `CatchItemSyntax`
- [x] `ClassDeclSyntax` @whiteio
- [ ] `ClassRestrictionTypeSyntax`
- [ ] `ClosureCaptureItemSpecifierSyntax`
- [ ] `ClosureCaptureItemSyntax`
- [ ] `ClosureCaptureSignatureSyntax`
- [ ] `ClosureExprSyntax`
- [ ] `ClosureParameterClauseSyntax`
- [ ] `ClosureParameterSyntax`
- [ ] `ClosureParamSyntax`
- [ ] `ClosureSignatureSyntax`
- [ ] `CodeBlockItemSyntax`
- [ ] `CodeBlockSyntax`
- [ ] `CompositionTypeElementSyntax`
- [ ] `CompositionTypeSyntax`
- [ ] `ConditionElementSyntax`
- [ ] `ConformanceRequirementSyntax` @andrewjl
- [ ] `ConstrainedSugarTypeSyntax`
- [ ] `ContinueStmtSyntax`
- [ ] `ConventionAttributeArgumentsSyntax`
- [ ] `ConventionWitnessMethodAttributeArgumentsSyntax`
- [ ] `DeclModifierDetailSyntax`
- [ ] `DeclModifierSyntax`
- [ ] `DeclNameArgumentsSyntax`
- [ ] `DeclNameArgumentSyntax`
- [ ] `DeclNameSyntax`
- [ ] `DeferStmtSyntax`
- [x] `DeinitializerDeclSyntax` @whiteio
- [ ] `DerivativeRegistrationAttributeArgumentsSyntax`
- [ ] `DesignatedTypeElementSyntax`
- [ ] `DictionaryElementSyntax`
- [ ] `DictionaryExprSyntax`
- [ ] `DictionaryTypeSyntax`
- [ ] `DifferentiabilityParamsClauseSyntax`
- [ ] `DifferentiabilityParamsSyntax`
- [ ] `DifferentiabilityParamSyntax`
- [ ] `DifferentiableAttributeArgumentsSyntax`
- [ ] `DiscardAssignmentExprSyntax`
- [ ] `DocumentationAttributeArgumentSyntax`
- [ ] `DoStmtSyntax`
- [ ] `DynamicReplacementArgumentsSyntax`
- [ ] `EditorPlaceholderDeclSyntax`
- [ ] `EditorPlaceholderExprSyntax`
- [ ] `EnumCaseDeclSyntax`
- [ ] `EnumCaseElementSyntax`
- [ ] `EnumCaseParameterClauseSyntax`
- [ ] `EnumCaseParameterSyntax`
- [x] `EnumDeclSyntax` @andrewjl
- [ ] `ExposeAttributeArgumentsSyntax`
- [ ] `ExpressionPatternSyntax`
- [ ] `ExpressionSegmentSyntax`
- [ ] `ExpressionStmtSyntax`
- [ ] `ExtensionDeclSyntax`
- [ ] `FallthroughStmtSyntax`
- [ ] `FloatLiteralExprSyntax`
- [ ] `ForcedValueExprSyntax`
- [ ] `ForgetStmtSyntax`
- [ ] `ForInStmtSyntax`
- [ ] `FunctionCallExprSyntax`
- [ ] `FunctionDeclSyntax`
- [ ] `FunctionEffectSpecifiersSyntax`
- [ ] `FunctionParameterSyntax`
- [ ] `FunctionSignatureSyntax`
- [ ] `FunctionTypeSyntax`
- [ ] `GenericArgumentClauseSyntax` @andrewjl
- [ ] `GenericArgumentSyntax` @andrewjl
- [ ] `GenericParameterClauseSyntax` @andrewjl
- [ ] `GenericParameterSyntax` @andrewjl
- [ ] `GenericRequirementSyntax` @andrewjl
- [ ] `GenericWhereClauseSyntax` @andrewjl
- [ ] `GuardStmtSyntax`
- [ ] `IdentifierExprSyntax`
- [ ] `IdentifierPatternSyntax`
- [ ] `IfConfigClauseSyntax`
- [ ] `IfConfigDeclSyntax`
- [ ] `IfExprSyntax`
- [ ] `ImplementsAttributeArgumentsSyntax`
- [ ] `ImplicitlyUnwrappedOptionalTypeSyntax`
- [x] `ImportDeclSyntax` @whiteio
- [ ] `InfixOperatorExprSyntax`
- [ ] `InheritedTypeSyntax`
- [ ] `InitializerClauseSyntax`
- [x] `InitializerDeclSyntax` @ahoppen
- [ ] `InOutExprSyntax`
- [ ] `IntegerLiteralExprSyntax`
- [x] `IsExprSyntax` @whiteio
- [ ] `IsTypePatternSyntax`
- [ ] `KeyPathComponentSyntax`
- [ ] `KeyPathExprSyntax`
- [ ] `KeyPathOptionalComponentSyntax`
- [ ] `KeyPathPropertyComponentSyntax`
- [ ] `KeyPathSubscriptComponentSyntax`
- [ ] `LabeledSpecializeEntrySyntax`
- [ ] `LabeledStmtSyntax`
- [ ] `LayoutRequirementSyntax` @andrewjl
- [ ] `MacroDeclSyntax`
- [ ] `MacroExpansionDeclSyntax`
- [ ] `MacroExpansionExprSyntax`
- [ ] `MatchingPatternConditionSyntax`
- [ ] `MemberAccessExprSyntax`
- [ ] `MemberDeclBlockSyntax`
- [ ] `MemberDeclListItemSyntax`
- [ ] `MemberTypeIdentifierSyntax`
- [ ] `MetatypeTypeSyntax`
- [ ] `MissingDeclSyntax`
- [ ] `MissingExprSyntax`
- [ ] `MissingPatternSyntax`
- [ ] `MissingStmtSyntax`
- [ ] `MissingSyntax`
- [ ] `MissingTypeSyntax`
- [ ] `MoveExprSyntax`
- [ ] `MultipleTrailingClosureElementSyntax`
- [ ] `NamedOpaqueReturnTypeSyntax`
- [ ] `NilLiteralExprSyntax`
- [ ] `ObjCSelectorPieceSyntax`
- [ ] `OpaqueReturnTypeOfAttributeArgumentsSyntax`
- [ ] `OperatorDeclSyntax`
- [ ] `OperatorPrecedenceAndTypesSyntax`
- [ ] `OptionalBindingConditionSyntax`
- [ ] `OptionalChainingExprSyntax`
- [ ] `OptionalTypeSyntax`
- [ ] `OriginallyDefinedInArgumentsSyntax`
- [ ] `PackElementExprSyntax`
- [ ] `PackExpansionExprSyntax`
- [ ] `PackExpansionTypeSyntax`
- [ ] `PackReferenceTypeSyntax`
- [ ] `ParameterClauseSyntax`
- [ ] `PatternBindingSyntax`
- [ ] `PostfixIfConfigExprSyntax`
- [ ] `PostfixUnaryExprSyntax`
- [ ] `PoundSourceLocationArgsSyntax`
- [ ] `PoundSourceLocationSyntax`
- [ ] `PrecedenceGroupAssignmentSyntax`
- [ ] `PrecedenceGroupAssociativitySyntax`
- [ ] `PrecedenceGroupDeclSyntax`
- [ ] `PrecedenceGroupNameElementSyntax`
- [ ] `PrecedenceGroupRelationSyntax`
- [ ] `PrefixOperatorExprSyntax`
- [ ] `PrimaryAssociatedTypeClauseSyntax`
- [ ] `PrimaryAssociatedTypeSyntax`
- [x] `ProtocolDeclSyntax` @whiteio
- [ ] `QualifiedDeclNameSyntax`
- [ ] `RegexLiteralExprSyntax`
- [ ] `RepeatWhileStmtSyntax`
- [ ] `ReturnClauseSyntax`
- [ ] `ReturnStmtSyntax`
- [ ] `SameTypeRequirementSyntax` @andrewjl
- [ ] `SequenceExprSyntax`
- [ ] `SimpleTypeIdentifierSyntax`
- [ ] `SourceFileSyntax`
- [ ] `SpecializeExprSyntax`
- [ ] `StringLiteralExprSyntax`
- [ ] `StringSegmentSyntax`
- [x] `StructDeclSyntax` @andrewjl
- [ ] `SubscriptDeclSyntax`
- [ ] `SubscriptExprSyntax`
- [ ] `SuperRefExprSyntax`
- [ ] `SwitchCaseLabelSyntax`
- [ ] `SwitchCaseSyntax`
- [ ] `SwitchDefaultLabelSyntax`
- [ ] `SwitchExprSyntax`
- [ ] `TargetFunctionEntrySyntax`
- [ ] `TernaryExprSyntax`
- [ ] `ThrowStmtSyntax`
- [ ] `TryExprSyntax`
- [ ] `TupleExprElementSyntax`
- [ ] `TupleExprSyntax`
- [ ] `TuplePatternElementSyntax`
- [ ] `TuplePatternSyntax`
- [ ] `TupleTypeElementSyntax`
- [ ] `TupleTypeSyntax`
- [ ] `TypealiasDeclSyntax`
- [ ] `TypeAnnotationSyntax`
- [ ] `TypeEffectSpecifiersSyntax`
- [ ] `TypeExprSyntax`
- [ ] `TypeInheritanceClauseSyntax`
- [ ] `TypeInitializerClauseSyntax`
- [ ] `UnavailableFromAsyncArgumentsSyntax`
- [ ] `UnderscorePrivateAttributeArgumentsSyntax`
- [ ] `UnresolvedAsExprSyntax`
- [ ] `UnresolvedIsExprSyntax`
- [ ] `UnresolvedPatternExprSyntax`
- [ ] `UnresolvedTernaryExprSyntax`
- [ ] `ValueBindingPatternSyntax`
- [ ] `VariableDeclSyntax`
- [ ] `VersionTupleSyntax`
- [ ] `WhereClauseSyntax`
- [ ] `WhileStmtSyntax`
- [ ] `WildcardPatternSyntax`
- [ ] `YieldExprListElementSyntax`
- [ ] `YieldListSyntax`
- [ ] `YieldStmtSyntax`