Add integration guide URLs for bufbuild/py and connectrpc/py (#2754)

Matches the other bufbuild and connectrpc plugins. I don't mind if you'd
rather close this out and just get these added on the next plugin
version bump, but figured I'd send this along anyway. Also, no strong
feeling on these exact URLs, just figured they ought to be populated.

Author: stefanvanburen

plugins/bufbuild/py/v0.5.0/buf.plugin.yaml

@@ -2,6 +2,7 @@ version: v1
 name: buf.build/bufbuild/py
 plugin_version: v0.5.0
 source_url: https://github.com/bufbuild/protobuf-py
+integration_guide_url: https://protobufpy.com/getting-started/quickstart/
 description: Generates idiomatic Python code from Protocol Buffers definitions using protobuf-py.
 spdx_license_id: Apache-2.0
 license_url: https://github.com/bufbuild/protobuf-py/blob/v0.5.0/LICENSE

plugins/connectrpc/py/v0.12.1/buf.plugin.yaml

@@ -2,6 +2,7 @@ version: v1
 name: buf.build/connectrpc/py
 plugin_version: v0.12.1
 source_url: https://github.com/connectrpc/connect-py
+integration_guide_url: https://connectrpc.com/docs/python/getting-started
 description: Generates client and server stubs for Connect Python. Compatible with the Connect RPC protocol.
 spdx_license_id: Apache-2.0
 license_url: https://github.com/connectrpc/connect-py/blob/v0.12.1/LICENSE