Document if Shutdown was called on the specific implementation

[hanyuancheung]

This PR clarify and document if Shutdown was called on the specific implementation instead of the interface.

• The interface does a good job outlining what implementations should do
• The implementation determine exactly how this is done and how that behavior is documented

Resolves #1694

[codecov]

Codecov Report

Merging #1989 (ac4f462) into main (87cc1e1) will decrease coverage by 0.0%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##            main   #1989     +/-   ##
=======================================
- Coverage   77.1%   77.1%   -0.1%     
=======================================
  Files        161     161             
  Lines       8593    8593             
=======================================
- Hits        6631    6629      -2     
- Misses      1701    1703      +2     
  Partials     261     261             

Impacted Files	Coverage Δ
sdk/trace/batch_span_processor.go	84.0% <ø> (ø)
sdk/trace/simple_span_processor.go	88.0% <ø> (ø)
exporters/trace/jaeger/jaeger.go	93.4% <0.0%> (-1.1%)	⬇️

[MrAlias]

These changes seem to be a restatement of the already existing documentation. I do not think these changes are worth including as they replace concise explications with verbose ones that say the same thing.

[Aneurysm9]

These changes seem to be a restatement of the already existing documentation. I do not think these changes are worth including as they replace concise explications with verbose ones that say the same thing.

Closing as there appears to be no need for this change.