Mark the AddLink() operation as stable.

[carlosalberto]

Fixes #3865

Enough SIGs have implemented prototypes without any concern. Also, no actual need to detect whether links were added before or after Span creation has received further attention, which previously was a blocker.

• Add links after activity (span) creation opentelemetry-dotnet#5273
• Add add_link API  opentelemetry-rust#1515
• Add Span#addLink, for adding link after span start opentelemetry-java#6084
• Add Span.add_link() method to add link after span start. opentelemetry-python#3618
• [API] Add a new AddLink() operation to Span opentelemetry-cpp#2380

[cijothomas]

Enough SIGs have implemented prototypes without any concern.

Is there anyway to find which SIGs have implemented this, given spec compliance matrix only shows C++?
See: #3865 (comment)

[carlosalberto]

@cijothomas This comment mentions of the ones we know of (only C++ and Java have merged the PRs though). Will check the other ones (plus update the matrix).

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 7 days.