[DOCS] update the INSTALL guide on cmake components

[dbarker]

Fixes #3408

Changes

• reference the opentelemetry-cpp::trace target instead of the interface only opentelemetry-cpp::sdk target
• add a note about the etw and elasticsearch components potential to be moved out of the core package

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[netlify]

✅ Deploy Preview for opentelemetry-cpp-api-docs canceled.

Name	Link
🔨 Latest commit	b03235c
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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.04%. Comparing base (0f8dedf) to head (b03235c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3422      +/-   ##
==========================================
+ Coverage   90.01%   90.04%   +0.03%     
==========================================
  Files         212      212              
  Lines        6932     6932              
==========================================
+ Hits         6239     6241       +2     
+ Misses        693      691       -2     

see 1 file with indirect coverage changes

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[marcalff]

LGTM, thanks for the fix.