docs: experimental features

[lukasmetzner]

We currently do not have a standardized approach for communicating experimental features, such as public betas or the utility functions included in our exp package.

This PR documents our understanding of experimental features, how to flag them as such, and updates existing features accordingly.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.08%. Comparing base (cdef517) to head (ef3309a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #680      +/-   ##
==========================================
- Coverage   79.20%   79.08%   -0.12%     
==========================================
  Files          50       50              
  Lines        4414     4414              
==========================================
- Hits         3496     3491       -5     
- Misses        703      706       +3     
- Partials      215      217       +2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[jooola]

✨

[jooola]

Looks good, I'll wait for all the other integrations to be ready and merge everything at once.