Drop website_docs folder

[chalin]

Contributes to open-telemetry/opentelemetry.io#720.

Note: I didn't find any mention of website_docs anywhere in the repo (other than the CHANGELOG, but that's ok), so there doesn't seem to be any links to fix.

/cc @austinlparker @dyladan

[codecov]

Codecov Report

Merging #2469 (ee01f00) into main (0f004da) will not change coverage.
The diff coverage is n/a.

❗ Current head ee01f00 differs from pull request most recent head cb14db6. Consider uploading reports for the commit cb14db6 to get more accurate results

@@           Coverage Diff           @@
##             main    #2469   +/-   ##
=======================================
  Coverage   93.20%   93.20%           
=======================================
  Files         137      137           
  Lines        5017     5017           
  Branches     1060     1060           
=======================================
  Hits         4676     4676           
  Misses        341      341