Clarify links a little

Innectic · web-flow · commit fdf910d2785e · 2018-07-01T14:41:30.000-07:00
diff --git a/README.md b/README.md
@@ -119,6 +119,8 @@ Arguments:
 
 The name of the portal that you have created previously using `/dimensify portal create`
 
+Pre-existing links on portals can be overriden using this command.
+
 * `destination_dimension`
 
 The name of the dimension that the portal should send the player to
