docs: fix docstring formatting (#93)

Committer: @parthea
PiperOrigin-RevId: 404756337
Source-Link: googleapis/googleapis@f034e5f
Source-Link: googleapis/googleapis-gen@8bb2d07
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiOGJiMmQwNzM1YTg2MWYyY2ZhZDRiOTA3MWYxY2FkNzQwNjVmNzY5NiJ9

Author: gcf-owl-bot[bot]

packages/google-devtools-artifactregistry/protos/google/devtools/artifactregistry/v1/artifact.proto

@@ -32,9 +32,9 @@ option ruby_package = "Google::Cloud::ArtifactRegistry::V1";
 // 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
+// * imageSizeBytes
+// * mediaType
+// * buildTime
 message DockerImage {
   option (google.api.resource) = {
     type: "artifactregistry.googleapis.com/DockerImage"