Delete website_docs since it has moved

[chalin]

• Delete website_docs because, as of Drop old and add new Java docs submodule opentelemetry.io#995, the OTel website pulls Java docs from https://github.com/open-telemetry/opentelemetry-java-docs
• Update references to the deleted directory
• Contributes to Move Java docs into this repo opentelemetry.io#989

/cc @austinlparker @trask

[codecov]

Codecov Report

Merging #4019 (54d99f1) into main (d88b09c) will increase coverage by 0.10%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #4019      +/-   ##
============================================
+ Coverage     89.88%   89.99%   +0.10%     
- Complexity     4297     4302       +5     
============================================
  Files           514      514              
  Lines         13011    13011              
  Branches       1261     1261              
============================================
+ Hits          11695    11709      +14     
+ Misses          913      900      -13     
+ Partials        403      402       -1     

Impacted Files	Coverage Δ
...telemetry/sdk/trace/export/BatchSpanProcessor.java	87.76% <0.00%> (-0.72%)	⬇️
...emetry/api/baggage/propagation/PercentEscaper.java	84.21% <0.00%> (+4.51%)	⬆️
...ntelemetry/sdk/extension/resources/OsResource.java	90.69% <0.00%> (+4.65%)	⬆️
...ava/io/opentelemetry/sdk/internal/RateLimiter.java	100.00% <0.00%> (+5.88%)	⬆️
...metry/sdk/extension/resources/ProcessResource.java	87.50% <0.00%> (+6.25%)	⬆️
...elemetry/sdk/extension/resources/HostResource.java	92.30% <0.00%> (+15.38%)	⬆️
...dk/extension/resources/ProcessRuntimeResource.java	100.00% <0.00%> (+16.66%)	⬆️

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[ghost]

LGTM!