chore(python): include docs/UPGRADING.md in docs/index.rst if it exists

synthtool/gcp/common.py

@@ -252,6 +252,10 @@ def py_library(self, **kwargs) -> Path:
         ):
             self.excludes += ["docs/index.rst"]
 
+        # Add kwargs to signal that upgrading.rst should be included in docs/index.rst if it exists
+        if Path("docs/upgrading.rst").exists():
+            kwargs["include_uprading_doc"] = True
+
         # Assume the python-docs-samples Dockerfile is used for samples by default
         if "custom_samples_dockerfile" not in kwargs:
             kwargs["custom_samples_dockerfile"] = False

synthtool/gcp/templates/python_library/docs/index.rst

@@ -14,16 +14,8 @@ API Reference
     {{ version }}/services
     {{ version }}/types
 {% endfor %}
-{%- if migration_guide_version %}
-Migration Guide
----------------
-
-See the guide below for instructions on migrating to the {{ migration_guide_version }} release of this library.
-
-.. toctree::
-    :maxdepth: 2
-
-    UPGRADING
+{% if include_uprading_doc %}
+.. include:: upgrading.rst
 {% endif %}
 Changelog
 ---------