docs build failed in `google-cloud-retail`

[parthea]

See https://github.com/googleapis/googleapis/blob/8242241358c63e091f749fce4c18c466172d2127/google/cloud/retail/v2alpha/project.proto#L178-L179 where there is an asterisk character which is not surrounded by backticks or escaped.

This caused the docs build to fail with

sphinx.errors.SphinxWarning: /home/runner/work/google-cloud-python/google-cloud-python/packages/google-cloud-retail/google/cloud/retail_v2alpha/types/project.py:docstring of google.cloud.retail_v2alpha.types.project.AlertConfig:5:Inline emphasis start-string without end-string.

Instead of

  // Required. Immutable. The name of the AlertConfig singleton resource.
  // Format: projects/*/alertConfig

It should be

  // Required. Immutable. The name of the AlertConfig singleton resource.
  // Format: `projects/*/alertConfig`

See https://github.com/googleapis/google-cloud-python/actions/runs/9453610393/job/26039343939?pr=12787

We should add a check upstream for unsupported formatting in proto comments

[parthea]

Transferring to google-cloud-python as the code for gapic-generator will be migrated there.

[parthea]

Closing as obsolete as we're no longer treating docs warnings as errors as of #16627