Add description for enabling experimental features

[bjee19]

Proposed changes

Add includes description for enabling experimental features and the risks that are associated with using experimental features.

Problem: There is insufficient documentation on enabling experimental features in our guides.

Solution: Add an includes description for enabling experimental features that we can use for any guides on experimental features. Also updated gateway api compatibility document.

Testing: Locally generated the documentation through Hugo and it works.

Closes #2481

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.29%. Comparing base (d242622) to head (b58bc2c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2546   +/-   ##
=======================================
  Coverage   89.29%   89.29%           
=======================================
  Files         100      100           
  Lines        7633     7633           
  Branches       50       50           
=======================================
  Hits         6816     6816           
  Misses        761      761           
  Partials       56       56           

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[kate-osborn]

LGTM

[ADubhlaoich]

LGTM! Added a number of suggestions and confirmed input from other reviewers, but nothing critically requires editing.

[ADubhlaoich]

Re-approved, responded to the threads. Good to resolve them all, didn't want to do it myself in case the context was missed.