update GitHub issue link in comment

less/component-animations.less

@@ -5,7 +5,7 @@
 // Heads up!
 //
 // We don't use the `.opacity()` mixin here since it causes a bug with text
-// fields in IE7-8. Source: https://github.com/twitter/bootstrap/pull/3552.
+// fields in IE7-8. Source: https://github.com/twbs/bootstrap/pull/3552.
 
 .fade {
   opacity: 0;