Set link from http:// to https://

For opensource.org/licenses/MIT!

Author: SuriyaaKudoIsc

README.md

@@ -21,7 +21,7 @@ License
 -------
 
 Bitcoin Core is released under the terms of the MIT license. See [COPYING](COPYING) for more
-information or see http://opensource.org/licenses/MIT.
+information or see https://opensource.org/licenses/MIT.
 
 Development Process
 -------------------