Tweak README for the last time

Author: Wes Cossick

README.md

@@ -265,7 +265,7 @@ var simplemde = new SimpleMDE({
 });
 ```
 
-Shortcuts are automatically converted between platforms. If you define a shortcut as "Cmd-B", on PC that shortcut will be changed to "Ctrl-B". Conversely, a shortcut defined as "Ctrl-I" will become "Cmd-I" in a browser of a Mac user.
+Shortcuts are automatically converted between platforms. If you define a shortcut as "Cmd-B", on PC that shortcut will be changed to "Ctrl-B". Conversely, a shortcut defined as "Ctrl-B" will become "Cmd-B" for Mac users.
 
 The list of actions that can be bound is the same as the list of built-in actions available for [toolbar buttons](#toolbar-icons).