alacritty.yml: Set a modifier to open URLs

Control key needs to be held to open URLs, this mimics GNOME terminal behavior.

alacritty.yml

@@ -393,7 +393,7 @@ mouse:
   # If this is `true`, the cursor is temporarily hidden when typing.
   hide_when_typing: true
 
-  #url:
+  url:
     # URL launcher
     #
     # This program is executed when clicking on a text which is recognized as a URL.
@@ -413,7 +413,7 @@ mouse:
     #
     # These are the modifiers that need to be held down for opening URLs when clicking
     # on them. The available modifiers are documented in the key binding section.
-    #modifiers: None
+    modifiers: Control
 
 # Mouse bindings
 #