Code File (Custom Classes) Docs (#363)

* Code File Docs

* Link from custom code section

* Apply suggestions from code review

Co-authored-by: Pooja Bhaumik <[email protected]>

* Address review comment

* Address review comment

* Add static class info

* Address review comments

* Actions into H3

* Review comments addressed!

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Co-authored-by: Pooja Bhaumik <[email protected]>

Author: pinkeshmars