Removes duplicated word *with* in README.md (qmk#29)

Author: cskeeters

README.md

@@ -16,7 +16,7 @@ This is a template repository which allows for an external set of QMK keymaps to
 1. Add your keymap(s) to the build by running `qmk userspace-add -kb <your_keyboard> -km <your_keymap>`
     * This will automatically update your `qmk.json` file
     * Corresponding `qmk userspace-remove -kb <your_keyboard> -km <your_keymap>` will delete it
-    * Listing the build targets can be done with with `qmk userspace-list`
+    * Listing the build targets can be done with `qmk userspace-list`
 1. Commit your changes
 
 ## Howto build with GitHub