docs(config): link to shared declarative config spec conformance matrix

[MikeGoldsmith]

Description

Adds a pointer from the Python SDK's declarative configuration package README to the shared language support status matrix in opentelemetry-configuration, so the Python conformance status lives alongside the other languages instead of being duplicated per language SDK.

Originally this PR added a Python-specific spec-conformance.md to the SDK repo. After discussion on open-telemetry/opentelemetry-js#6846 (where the same approach was being taken there), the consensus is that conformance status should be tracked once in the shared config repo, not duplicated per language. Reworked accordingly:

• Drop the in-tree spec-conformance.md.
• Update the SDK config package README with a "Spec conformance" section pointing at the shared matrix and noting that schema/meta_schema_language_python.yaml in the config repo is the source of truth.
• Rewrite the changelog fragment to describe the new shape.

Closes #5346.

Dependencies

• docs: add python to known languages opentelemetry-configuration#668 (adds python to the shared matrix as unknown entries). The link in this PR resolves only after that merges. A follow-up PR against the config repo will replace the unknown entries with the real Python status.

Type of change

• This change requires a documentation update

How Has This Been Tested?

• tox -e docs builds clean.

Does This PR Require a Contrib Repo Change?

• Yes.
• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[herin049]

Does adding it here not work?

[ocelotl]

Does adding it here not work?

@MikeGoldsmith I wonder what is the motivation for this PR, is the compliance matrix in the spec not detailed enough?

In any case, having this new matrix here is harmless but I understand the point of @herin049 above, I am also curious.

[MikeGoldsmith]

You're both right, I'm going to update to link to the compatability matrix in the config repo itself. Although, python is on that list yet, so I'll work on adding it there first 👍🏻

[xrmx]

Blocker until we get the config repo updated