Improve expression syntax documentation

[sruenwg]

Closes #1102
Closes #724

This changes the expression syntax documented on the Expressions page to follow the patterns proposed in #1102.
Some incorrectly documented syntaxes were fixed in the process.

match before:

match after:

in before:

in after:

Launch Checklist

• Confirm your changes do not include backports from Mapbox projects (unless with compliant license) - if you are not sure about this, please ask!
• Briefly describe the changes in this PR.
• Link to related issues.
• Include before/after visuals or gifs if this PR includes visual changes.
• Write tests for all new functionality.
• Document any changes to public APIs.
• Post benchmark scores.
• Add an entry to CHANGELOG.md under the ## main section.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.67%. Comparing base (b4d8978) to head (6d12492).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1112   +/-   ##
=======================================
  Coverage   93.67%   93.67%           
=======================================
  Files         115      115           
  Lines        4935     4935           
  Branches     1403     1403           
=======================================
  Hits         4623     4623           
  Misses        312      312           

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[HarelM]

Thanks for this great effort!
I've added a few comments, nothing major.
Once addressed, I'll merge this.

[sruenwg]

Thanks for the comments @HarelM!
Please check the updated version + my comments whenever you are able to, thanks again 🙇

[HarelM]

Just to be on the safe side, although this doesn't change the logic, let's add a changelog entry if anyone is relaying on the current v8 content.

[HarelM]

THANKS!!!