Merge branch 'mo-pipeline-artifact-comment' into 'master'

Explain what Ci::PipelineArtifact is

See merge request gitlab-org/gitlab!38926

app/models/ci/pipeline_artifact.rb

 # frozen_string_literal: true
 
-# This class is being used to persist generated report consumable by gitlab frontend in a pipeline context.
+# This class is being used to persist additional artifacts after a pipeline completes, which is a great place to cache a computed result in object storage
 
 module Ci
   class PipelineArtifact < ApplicationRecord