Version 6.0 Release

[oojacoboo]

This PR prepares for a version 6.0 release

• Updateded Docusaurus and Node for CI workflows
• Updated documentation for 6.0 changes
• Added new README for doc website development/deployment

[codecov-commenter]

Codecov Report

Merging #483 (0278aff) into master (8078bc2) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #483   +/-   ##
=========================================
  Coverage     95.78%   95.78%           
  Complexity     1773     1773           
=========================================
  Files           153      153           
  Lines          4481     4481           
=========================================
  Hits           4292     4292           
  Misses          189      189           

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