[Python Otel] Fix packaging issue (v1.62.x backport) (#35936)

Backport of #35929 to v1.62.x.
---


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src/python/grpcio_observability/README.rst

@@ -1,11 +1,12 @@
 gRPC Python Observability
-===========
+=========================
+
 Package for gRPC Python Observability.
 
 More details can be found in `OpenTelemetry Metrics gRFC <https://github.com/grpc/proposal/blob/master/A66-otel-stats.md#opentelemetry-metrics>`_.
 
 How gRPC Python Observability Works
--------------------------
+-----------------------------------
 
 gRPC Python is a wrapper layer built upon the gRPC Core (written in C/C++). Most of telemetry data
 is collected at core layer and then exported to Python layer. To optimize performance and reduce

src/python/grpcio_observability/setup.py

@@ -41,7 +41,7 @@
 _parallel_compile_patch.monkeypatch_compile_maybe()
 
 CLASSIFIERS = [
-    "Private :: Do Not Upload",
+    "Development Status :: 4 - Beta",
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
     "License :: OSI Approved :: Apache Software License",
@@ -274,6 +274,7 @@ def extension_modules():
     name="grpcio-observability",
     version=grpc_version.VERSION,
     description="gRPC Python observability package",
+    long_description_content_type="text/x-rst",
     long_description=open(README_PATH, "r").read(),
     author="The gRPC Authors",
     author_email="grpc-io@googlegroups.com",