Docs: migration guides for new package versions

[lukegalbraithrussell]

Summary

previews:

• changelog entry (this is in the docs repo)
• migration overview page
• web-api migration guide
• webhook migration guide
• socket-mode migration guide

Requirements

• 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.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 35aac2f

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.86%. Comparing base (aeaf9f9) to head (35aac2f).
⚠️ Report is 19 commits behind head on v8.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##               v8    #2606      +/-   ##
==========================================
+ Coverage   87.50%   88.86%   +1.35%     
==========================================
  Files          62       62              
  Lines       10230    10230              
  Branches      418      450      +32     
==========================================
+ Hits         8952     9091     +139     
+ Misses       1256     1117     -139     
  Partials       22       22              

Flag	Coverage Δ
cli-hooks	88.86% <ø> (+1.35%)	⬆️
cli-test	88.86% <ø> (+1.35%)	⬆️
logger	88.86% <ø> (+1.35%)	⬆️
oauth	88.86% <ø> (+1.35%)	⬆️
socket-mode	88.86% <ø> (+1.35%)	⬆️
web-api	88.86% <ø> (+1.35%)	⬆️
webhook	88.86% <ø> (+1.35%)	⬆️

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[WilliamBergamin]

Nice work 🥇 left a few comments mainly about remove some stuff 🙏

Maybe we should merge this branch in the v8 instead of main that was we can merge everything at the same time 🤔 at the same time there might be a delay between merging and releasing

[lukegalbraithrussell]

@WilliamBergamin addressed all your feedback! (removed the stuff that should be removed, and swapped Option A and Option B for each)