Update README.md

Made explicit HTTPS calls

Author: alanyee

README.md

@@ -1,11 +1,11 @@
 twitter.github.com
 ======
 
-The source code of http://twitter.github.io/
+The source code of https://twitter.github.io/
 
 LICENSE
 ------------
 
 Copyright 2012 Twitter, Inc.
 
-Licensed under the Apache License, Version 2.0: http://www.apache.org/licenses/LICENSE-2.0
+Licensed under the Apache License, Version 2.0: https://www.apache.org/licenses/LICENSE-2.0