docs: update docs and scripts to lock release-0.8 branch into latest stable release

[krancour]

This PR locks the docs in release-0.8 (which are the current production docs) into v0.8.7 of the chart and quickstart scripts from the release-0.8 branch.

This will keep what are now the production docs working correctly even as we begin to tackle v0.9.0-specific release chores in main.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.71%. Comparing base (bf3c727) to head (5975b4f).
Report is 1 commits behind head on release-0.8.

Additional details and impacted files

@@             Coverage Diff              @@
##           release-0.8    #2611   +/-   ##
============================================
  Coverage        46.71%   46.71%           
============================================
  Files              246      246           
  Lines            17754    17754           
============================================
  Hits              8293     8293           
  Misses            9030     9030           
  Partials           431      431           

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