docs: clarify FileInstallationStore and FileStateStore are dev-only

[mwbrooks]

Summary

This pull request addresses a reported security issue where a developer was using the FileStateStore for production and reported security vulnerabilities.

We already clarify that FileInstallationStore is for development only and this PR extends the paragraph to include FileStateStore.

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[lukegalbraithrussell]

Looks good but am also open to making this a big red callout card if needed

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.09%. Comparing base (9a0c4c4) to head (4566ff3).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2446   +/-   ##
=======================================
  Coverage   93.09%   93.09%           
=======================================
  Files          40       40           
  Lines       11240    11240           
  Branches      713      713           
=======================================
  Hits        10464    10464           
  Misses        764      764           
  Partials       12       12           

Flag	Coverage Δ
cli-hooks	95.23% <ø> (ø)
cli-test	94.79% <ø> (ø)
oauth	77.39% <ø> (ø)
socket-mode	61.87% <ø> (ø)
web-api	98.11% <ø> (ø)
webhook	96.66% <ø> (ø)

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[mwbrooks]

@lukegalbraithrussell Oh, interesting! It's your call, but that could be a good idea to do somewhere in the docs. Would you use the :::warning syntax?

[zimeg]

@mwbrooks LGTM and thanks for making this more clear!

I left a few comments on separating sections and think in follow up PRs we can improve the jsdoc for these classes, but please let me know what you think!