update opensource.org reference at readme (enable SSL)
@ -43,7 +43,7 @@ The above command downloads and runs a [pre-built image](https://registry.hub.do
## License
Bitcoin is released under the terms of the MIT license. See `COPYING` for more
information or see http://opensource.org/licenses/MIT.
information or see https://opensource.org/licenses/MIT.
libtorrent is released under the BSD-license.