Use mkhelp to print help message

src/ffoo/saturnin_meta.sh

 ffoo import pretty
 
 saturnin_help() {
-    echo ""
-    echo "built-in sub-commands:"
-    echo ""
-    echo "    conf"
-    echo "    help"
-    echo ""
-    echo "installed sub-commands:"
-    echo ""
-    saturnin_lssc | sed -e 's/^/    /'
+    {
+        echo "built-in commands:"
+        echo "    conf"
+        echo "    help"
+        echo ""
+        echo "installed commands:"
+        saturnin_lssc \
+          | sed -e 's/^/    /'
+    } | mkhelp -E -f -
     return "$FFOO_EXIT_OK"
 }