Add link to SQL docs and update info about SQL syntax

Product: Tarantool
Since: ?
Audience/target: SQL users
Root document: https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_statements_and_clauses/
SME: @ ImeevMA

Details

Some parts of SQL syntax are not described in docs. (E.g.: there is SUM ALL in https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#e091-set-functions , but ALL qualifier is missed in https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_statements_and_clauses/#aggregate-functions .

Also, https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#e091-set-functions has missing links to some syntax definitions.

Definition of done

• Add links
• Add missing syntax description

Planning checklist

• E011-06 | Implicit casting among the numeric data types - Add missing link (https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_user_guide/#sql-data-type-conversion or https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_user_guide/#operators)
• E051-01 | SELECT DISTINCT - Add missing link (https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_statements_and_clauses/#select)
• E051-04 | GROUP BY can contain columns not in select list - Add missing link (https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_statements_and_clauses/#sql-group-by)
• E051-05 | Select list items can be renamed - Add missing link (https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_statements_and_clauses/#select-list)
• E051-07 | Qualified * in SELECT list - Add missing link (https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_statements_and_clauses/#select-list)
• E051-08 | Correlation names in the FROM clause - Add missing link (https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_statements_and_clauses/#from-clause)
• E061-01 | Comparison predicate - Add missing link (https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_user_guide/#operators)
• E061-03 | IN predicate with list of values - Add missing link (https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_user_guide/#operators)
• E061-05 | LIKE predicate: ESCAPE clause - Add missing link (https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_user_guide/#sql-operator-like)

Add missing links:

• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#e061-basic-predicates-and-search-conditions
• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#e061-basic-predicates-and-search-conditions
• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#e091-set-functions (all|distinct - https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_statements_and_clauses/#select)
• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#e091-set-functions
• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#e131-null-value-support
• tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#e141-basic-integrity-constraints
• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#f041-basic-joined-table
• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#f081-union-and-except-in-views
• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#f131-grouped-operations
• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#f261-case-expression (https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_user_guide/#expressions?)
• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#f-other
• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#t321-basic-sql-invoked-routines
• https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql-features/#t-other

Start with the SQL statements and clauses document and the SQL features page listed in the issue, then compare the E011, E051, E061, and E091 checklist items with the linked SQL user guide sections. Update the documented links and add the missing syntax descriptions, including the ALL qualifier for aggregate functions. Done means the listed feature entries link to the relevant documentation and the missing syntax is described.