Update docs for 1.9.0 release

[anuraaga]

No description provided.

[codecov]

Codecov Report

Merging #3866 (c40539d) into main (82e2bc2) will increase coverage by 0.06%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #3866      +/-   ##
============================================
+ Coverage     89.70%   89.76%   +0.06%     
- Complexity     4230     4233       +3     
============================================
  Files           504      504              
  Lines         13059    13059              
  Branches       1274     1274              
============================================
+ Hits          11715    11723       +8     
+ Misses          915      909       -6     
+ Partials        429      427       -2     

Impacted Files	Coverage Δ
.../incubator/trace/ExecutorServiceSpanProcessor.java	91.96% <0.00%> (-0.90%)	⬇️
...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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[jkwatson]

Thanks!