Docs: Organize meta and describe visitor in Working with Rules

[pedrottimark]

• bulleted list of rule files so it would be easy to add rule doc
• bulleted lists of meta properties (see Add support for metadata to all rules #5417) and illustrated them in the first source file example
• use terms visit (verb) and visitor (noun) discussed in Naming convention: Visitors / event-handlers? #5843 @jfmengels Can you please critique?
• use terms event and handler for code path analysis @mysticatea Can you please critique?
• illustrate visitors and handlers from array-callback-return in the second source file example

[eslintbot]

LGTM

[mention-bot]

By analyzing the blame information on this pull request, we identified @ilyavolodin, @evangoer and @nzakas to be potential reviewers

[platinumazure]

Am I missing something? This property needs a value (there is no fallthrough of object key/value pairs).

[pedrottimark]

@platinumazure You will smile. I woke up this morning thinking how I left out the case keywords at the fallthrough for function expressions, and then, oh noooo!

[platinumazure]

It's okay, we all have days like that. Good work on these docs!

[eslintbot]

LGTM

[jfmengels]

LGTM :)

[nzakas]

Waiting on feedback from @mysticatea

[eslintbot]

LGTM

[pedrottimark]

Motivated by discussion in chat, added under Applying Fixes an Important note about meta.fixable property with a link to Rule Basics.

[nzakas]

Lgtm. Would rather merge in now and update later if we find problems.