Group verbs in help text

If many verbs (tens or hundreds) are implemented, it's very difficult to find a verb. So it would be useful to be able to group them in the help text, perhaps by sections that can be defined as properties of the VerbAttribute.

Example:

```csharp
[Verb("my-verb1", HelpText = "MyVerb1 help", HelpSection = "Section 1")]
class MyVerb1Options
{ ... }

[Verb("my-verb2", HelpText = "MyVerb2 help", HelpSection = "Section 2")]
class MyVerb2Options
{ ... }
```

The output in the console should then group verbs based on their own section.

Start by locating VerbAttribute and the code that formats verbs in the console help output. Trace how verb metadata is collected, then define the section property and verify that verbs with matching sections appear together while the help output remains usable for unsectioned verbs.

Written by the indexing model from the issue text.