fix(config): call ActiveWindowBorderColour correctly

The sample config only provided three of the four required arguments in
the example call to ActiveWindowBorderColour. Uncommenting the line as
it was would raise an error from AuthoHotKey.

komorebi.sample.ahk

@@ -24,7 +24,7 @@ InvisibleBorders(7, 0, 14, 7)
 WorkspaceName(0, 0, "I")
 
 ; Uncomment the next two lines if you want a visual border drawn around the focused window
-; ActiveWindowBorderColour(66, 165, 245) ; this is a nice blue colour
+; ActiveWindowBorderColour(66, 165, 245, "single") ; this is a nice blue colour
 ; ActiveWindowBorder("enable")
 
 ; Allow komorebi to start managing windows