Remove defunct link from gh actions

The online guide that was GitHub CLI-specific no longer exists. Instead,
"GitHub CLI" sections were added to existing individual articles about
managing workflow runs.

pkg/cmd/actions/actions.go

@@ -56,8 +56,5 @@ func actionsExplainer(cs *iostreams.ColorScheme) string {
 			gh workflow run:      Trigger a workflow_dispatch run for a workflow file
 
 			To see more help, run 'gh help workflow <subcommand>'
-
-			For more in depth help including examples, see online documentation at:
-			<https://docs.github.com/en/actions/guides/managing-github-actions-with-github-cli>
 		`, header, runHeader, workflowHeader)
 }