Update README

Signed-off-by: Matt Friedman <maf675@gmail.com>

Author: iMattPro

README.md

@@ -30,4 +30,4 @@ This is the repository for the development of the phpBB Board Rules Extension.
 * Translations should be posted to the [Board Rules topic at phpBB.com](https://www.phpbb.com/customise/db/extension/boardrules/support/topic/130746). We accept pull requests for translation corrections, but we do not accept pull requests for new translations.
 
 ## License
-[GNU General Public License v2](http://opensource.org/licenses/GPL-2.0)
+[GNU General Public License v2](https://opensource.org/licenses/GPL-2.0)