Update status of stdout exporter for logs to stable

[cijothomas]

https://github.com/open-telemetry/opentelemetry-specification/pull/3741/files and https://github.com/open-telemetry/opentelemetry-specification/pull/3740/files were added together, and it is not clear why one is experimental, and the other is stable.

This PR is marking the logging stdout exporter spec as stable. I couldn't find any reason why it was non-stable in the first place, so I assume it was just an oversight only. Happy to be corrected, if I missed something

Fixes #

Changes

Please provide a brief description of the changes here.

For non-trivial changes, follow the change proposal process.

• Related issues #
• Related OTEP(s) #
• Links to the prototypes (when adding or changing features)
• CHANGELOG.md file updated for non-trivial changes
• spec-compliance-matrix.md updated if necessary

[github-actions]

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

[carlosalberto]

@open-telemetry/specs-logs-approvers please review

Also @cijothomas we usually, for PR purposes, don't create branches from this very repo, but from our personal ones, etc.

[cijothomas]

@open-telemetry/specs-logs-approvers please review

Also @cijothomas we usually, for PR purposes, don't create branches from this very repo, but from our personal ones, etc.

that was my mistake! I used browser to edit, assuming it creates branch in my fork!

[cijothomas]

closing in favor of #3922 as this was branched in this repo, not a fork.

[reyang]

I've cleaned up personal branches for this repo.