documentation docs: rewrite pattern matching documentation

This PR proposes a rewrite in the pattern matching documentation for better clarity and organization.

I first started to fix the final section about Matching on Caller ID, but then I realized that the whole document could be further improved.

I'm willing to change it based on your suggestions.

I need some clarification:

Special Symbols The only characters with special meaning within a set are the '-' character, to define a range between two characters, the '\' character to escape a special character available within a set, and

What is the other character with special meaning? Notice the final and ...

Auto-Fallthrough Please be aware that because of the way auto-fallthrough works, if Asterisk can't find the next priority number for the current extension or pattern match, it will also look for that same priority in a less specific pattern match.

If I write it as "it will look for that next priority in a less specific pattern match", does it still represents the correct behaviour? I thought it's clearer.

Wildcards

Only ! is used for overlap dialing or . can also be used? Is this the difference that the old text was talking about?

Overlap dialing

I couldn't find nothing regarding overlap dialing on the Asterisk docs. Does this page exist? We could link it here. If it's missing, we can write something in that matter (example)

Resolves: https://github.com/asterisk/documentation/issues/56