add tag command to grep for tag

bash/tag.sh

@@ -0,0 +1,2 @@
+# just list the files so we can pipe it.
+grep -l "\+ $@" *md

bash/um

@@ -18,8 +18,10 @@ case "$1" in
     rename)
         $UMBASEPATH/rename.sh "${@:2}"
         ;;
+    tag)
+        $UMBASEPATH/tag.sh "${@:2}"
+        ;;
     *)
-        # else
+        echo "usage: um (next|last|cat|rename|tag)"
-        echo "usage: um (next|last|cat|rename)"
         ;;
 esac