Drop website_docs and docs_update workflow

[chalin]

• Closes Move website_docs back to website repo #280
• Contributes to Ensure that all doc pages have a single source repo opentelemetry.io#730
• Note that I moved the most recent doc changes to the website repo via Erlang doc updates opentelemetry.io#801

/cc @austinlparker @tsloughter

[codecov]

Codecov Report

Merging #285 (e09b654) into main (9565e4f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #285   +/-   ##
=======================================
  Coverage   36.58%   36.58%           
=======================================
  Files          45       45           
  Lines        3187     3187           
=======================================
  Hits         1166     1166           
  Misses       2021     2021           

Flag	Coverage Δ
api	62.44% <ø> (ø)
elixir	15.91% <ø> (ø)
erlang	36.53% <ø> (ø)
exporter	19.75% <ø> (ø)
sdk	79.12% <ø> (ø)

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