Fix Markdown problems in LICENSE.mkd

LICENSE.mkd

@@ -4,11 +4,10 @@
 
 ## Source code license
 
-Before version 1.0, Pubwich was released under a [Creative Commons BY-SA][cc] license. However, since version 1.0, Pubwich source code is released under the open-source [GPL 2.0][gpl] license, which means that you can use and modify the code freely (even for commercial use). However, if you want to distribute your modified code, you must release it under the same license.
+Before version 1.0, Pubwich was released under a [Creative Commons BY-SA](cc) license. However, since version 1.0, Pubwich source code is released under the open-source GPL 2.0 license, which means that you can use and modify the code freely (even for commercial use). However, if you want to distribute your modified code, you must release it under the same license.
 
 ## External libraries
 
 Cache_Lite, Mustache.php, PHP OAuth, PHP Gettext and Zend_Json libraries are included with their respective copyright notices.
 
-[cc]: http://creativecommons.org/licenses/by-sa/2.0/ca/deed.en_CA
-[gpl]: See the `GPL.txt` text file in Pubwich root directory for the complete license
+[cc]: http://creativecommons.org/licenses/by-sa/2.0/ca/deed.en_CA