Restore help footer

At the moment, the "help footer" doesn't add any new information, but if
additional flags are added later, they should appear in the footer. This
change restores this help footer:

```shell
USAGE
  gh actions [flags]

INHERITED FLAGS
  --help   Show help for command

LEARN MORE
  Use 'gh <command> <subcommand> --help' for more information about a command.
  Read the manual at https://cli.github.com/manual
```

pkg/cmd/actions/actions.go

@@ -1,8 +1,6 @@
 package actions
 
 import (
-	"fmt"
-
 	"github.com/MakeNowJust/heredoc"
 	"github.com/cli/cli/pkg/cmdutil"
 	"github.com/cli/cli/pkg/iostreams"
@@ -10,19 +8,17 @@ import (
 )
 
 func NewCmdActions(f *cmdutil.Factory) *cobra.Command {
+	cs := f.IOStreams.ColorScheme()
+
 	cmd := &cobra.Command{
 		Use:   "actions",
 		Short: "Learn about working with GitHub actions",
+		Long:  actionsExplainer(cs),
 		Annotations: map[string]string{
 			"IsActions": "true",
 		},
 	}
 
-	cmd.SetHelpFunc(func(c *cobra.Command, s []string) {
-		cs := f.IOStreams.ColorScheme()
-		fmt.Fprintln(f.IOStreams.Out, actionsExplainer(cs))
-	})
-
 	return cmd
 }