Issue with generated docstring in Artifact Registry V1

[parthea]

There is a sphinx warning when generating the docs for Artifact Registry V1.

The source proto here, has the following comment:

// DockerImage represents a docker artifact.
// The following fields are returned as untyped metadata in the Version
// resource, using camelcase keys (i.e. metadata.imageSizeBytes):
//   - imageSizeBytes
//   - mediaType
//   - buildTime

The docstring that is generated based on the above code looks incorrectly formatted. See below:

    r"""DockerImage represents a docker artifact.
    The following fields are returned as untyped metadata in the
    Version resource, using camelcase keys (i.e.
    metadata.imageSizeBytes):   - imageSizeBytes
      - mediaType
      - buildTime

Sphinx is reporting this warning, which is causing our docs build to fail in googleapis/python-artifact-registry#80 since we're treating warnings as errors.

sphinx.errors.SphinxWarning: /usr/local/google/home/partheniou/python-artifact-registry/google/cloud/artifactregistry_v1/types/artifact.py:docstring of google.cloud.artifactregistry_v1.types.artifact.DockerImage:5:Unexpected indentation.

Warning, treated as error:
/usr/local/google/home/partheniou/python-artifact-registry/google/cloud/artifactregistry_v1/types/artifact.py:docstring of google.cloud.artifactregistry_v1.types.artifact.DockerImage:5:Unexpected indentation.
nox > Command sphinx-build -W -T -N -b html -d docs/_build/doctrees/ docs/ docs/_build/html/ failed with exit code 2
nox > Session docs failed.

I found that the following docstring would not cause the sphinx build to fail so I've added a workaround in owlbot.py in googleapis/python-artifact-registry#80 to allow the PR to be merged.

    r"""DockerImage represents a docker artifact.
    The following fields are returned as untyped metadata in the
    Version resource, using camelcase keys (i.e.
    metadata.imageSizeBytes):

      - imageSizeBytes
      - mediaType
      - buildTime

[parthea]

Fix proposed in internal cl/404229788

[parthea]

Resolved with cl/404229788