Typo within strings.properties (#30)

Author: finglis

src/main/resources/qupath/ext/template/ui/strings.properties

@@ -3,7 +3,7 @@ title = Demo extension
 name = My Java extension
 description = This is just a demo to show how extensions work
 menu.enable = Enable my extension
-menu.description = Click this buton to enable the demo extension
+menu.description = Click this button to enable the demo extension
 
 stage.title = Demo dialog
 option.integer.text = An option: