Add password notice to installation instructions.

Author: qw3rtman

README.md

@@ -27,7 +27,7 @@ You can see the current local branch and its respective remote branch, the lates
 curl -fsSL git.io/gg.sh | sh
 ```
 
-All this installation script does is download the `gg` script, make it an executable, and copy it to your $PATH (/usr/local/bin).
+All this installation script does is download the `gg` script, make it an executable, and copy it to your $PATH (/usr/local/bin). For copying to your $PATH, it may require you to enter your password. If there is a better way to do this, please send in a pull request.
 
 If you don't feel comfortable executing a random script, [its source is available here](https://github.com/qw3rtman/gg/blob/master/install.sh).