Fix docs build on RTD: More dependencies needed
Fix docs build on RTD: More dependencies needed

This isn't a problem during our docker build because the other
deps are already installed when the docs file installed. But on
RTD it only installs the docs.txt file.

flodolo/bedrock,craigcook/bedrock,pascalchevrel/bedrock,craigcook/bedrock,flodolo/bedrock,pascalchevrel/bedrock,craigcook/bedrock,flodolo/bedrock,alexgibson/bedrock,craigcook/bedrock,sylvestre/bedrock,mozilla/bedrock,alexgibson/bedrock,alexgibson/bedrock,mozilla/bedrock,pascalchevrel/bedrock,sylvestre/bedrock,alexgibson/bedrock,sylvestre/bedrock,sylvestre/bedrock,mozilla/bedrock,pascalchevrel/bedrock,mozilla/bedrock,flodolo/bedrock