Update stages.yml for Pipeline Execution/Pipeline Authoring
Why is this change being made?
Updates Technical Writer assignment for grouppipeline execution and grouppipeline authoring per Transition Verify/Pipeline Execution (50%) TW a... (gitlab-org/technical-writing#951 - closed) and Transition Verify/Pipeline Authoring (50%) TW a... (gitlab-org/technical-writing#952 - closed).