Fix link to correct license on contributing document
Fix link to correct license on contributing document

The link on the contributing page links to the Twitter Bootstrap license file
which is MIT, not APLv2.

kristopolous/BOOTSTRA.386,kidGodzilla/BOOTSTRA.386,DBosley/BOOTSTRA.386,drkyro/BOOTSTRA.386,kristopolous/BOOTSTRA.386,DBosley/BOOTSTRA.386,AndreasZeissner/BOOTSTRA.386,kristopolous/BOOTSTRA.386,kidGodzilla/BOOTSTRA.386,drkyro/BOOTSTRA.386,drkyro/BOOTSTRA.386,drkyro/BOOTSTRA.386,AndreasZeissner/BOOTSTRA.386,AndreasZeissner/BOOTSTRA.386,kristopolous/BOOTSTRA.386,AndreasZeissner/BOOTSTRA.386,kidGodzilla/BOOTSTRA.386,drkyro/BOOTSTRA.386,kidGodzilla/BOOTSTRA.386,kristopolous/BOOTSTRA.386,kidGodzilla/BOOTSTRA.386