Build protobuf documentation reference during docs release action

[geel9]

Modifies the release-docs GitHub action to build the Protobuf reference markdown file before building and shipping the docs.

Without this step, said Protobuf Reference will only be updated when a developer manually executes devops/generate_proto_files.py and pushes the file to the repo.

Thoughts:

• Maybe this should only happen when we release a new tagged version of the SDK?
  • Ensures that newer proto files, which haven't been released in the SDK yet, are not documented before they should be.

[fundthmcalculus]

add pip install -r ./devops/requirements.txt to the previous run action, and this should be good.