• Remove buf beta registry {plugin,template} {deprecate,undeprecate}.
• Add --user and --netrc flags to buf curl, providing the same behavior as the
  flags of the same name in the cURL tool.
• Include DocumentationPath in the module on buf push.
• Support fallback paths, README.md and README.markdown, for module documentation.
  The default source for module documentation is buf.md.
  If buf.md is missing, README.md or README.markdown is used as fallback sources.