Use HTTPS for URLs in README

Author: jwakely

README

@@ -2,10 +2,10 @@ https://github.com/cplusplus/LWG is the repository for the C++ Standards Committ
 Library Working Group issues lists files. 
 
 For the most recent draft of the lists generated from these files, see
-http://cplusplus.github.io/LWG/lwg-active.html 
+https://cplusplus.github.io/LWG/lwg-active.html
 
 For the official (but less up-to-date) versions of these lists, see
-http://www.open-std.org/jtc1/sc22/wg21/
+https://www.open-std.org/jtc1/sc22/wg21/
 
 To submit a new issue, please read
 https://cplusplus.github.io/LWG/lwg-active.html#submit_issue