docs(config): publish declarative config spec conformance matrix

[MikeGoldsmith]

Description

There is no published view of which fields of the OpenTelemetry declarative configuration schema the Python SDK currently applies. That makes it hard to define "most use cases covered" for a 1.0 recommendation, to communicate gaps to users and vendors, and to compare coverage against Go, Java, and JS.

This PR adds the matrix:

• New doc at opentelemetry-sdk/src/opentelemetry/sdk/_configuration/spec-conformance.md listing every schema section (resource, propagator, tracer/meter/logger providers, attribute_limits, OTLP exporter properties, sampler, id_generator, configurators, exemplar filter, views) with a tri-state status (✅ Supported / ⚠️ Partial / ❌ Unsupported) and links to tracking issues for the gaps.
• SDK configuration package README links to the matrix.
• Changelog entry under Documentation.

Mirrors the equivalent JS doc landed in open-telemetry/opentelemetry-js#6846 (tracked via open-telemetry/opentelemetry-js#6809).

Fixes #5346. Part of #3631.

Type of change

• This change requires a documentation update

How Has This Been Tested?

• Every row cross-checked against the factories under opentelemetry-sdk/src/opentelemetry/sdk/_configuration/_*.py and the regenerated models.py, not just the schema.
• Gaps point at the existing trackers (feat(config): add metric producer support to declarative config #5073, feat(config): unify declarative and env-var configuration through a shared SDK orchestrator #5126, declarative config: detect and log missing dependencies #5229, feat(config): support OTEL_CONFIG_FILE in the SDK configurator #5271, feat(config): validate declarative config file_format version #5315, feat(config): bump declarative configuration schema to v1.1.0 #5333, feat(config): wire id_generator from declarative configuration to TracerProvider #5334, feat(config): decide OTEL_PYTHON_* env-var behaviour when OTEL_CONFIG_FILE is set #5335) and explicitly note "no tracker yet" for items not currently tracked (top-level log_level, attribute_limits, instrumentation/development, distribution, configurators, log-record limits, Prometheus secondary flags, View attribute_keys.excluded, jaeger_remote sampler, otlp_file exporters).

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.