README: convert links from http: to https:

Author: generalmimon

README.md

@@ -12,9 +12,9 @@ formats, network stream packet formats, etc.
 
 Further reading:
 
-* [About Kaitai Struct](http://kaitai.io/)
-* [About API implemented in this library](http://doc.kaitai.io/stream_api.html)
-* [JavaScript-specific notes](http://doc.kaitai.io/lang_javascript.html) - also includes Quick start guide
+* [About Kaitai Struct](https://kaitai.io/)
+* [About API implemented in this library](https://doc.kaitai.io/stream_api.html)
+* [JavaScript-specific notes](https://doc.kaitai.io/lang_javascript.html) - also includes Quick start guide
 
 ## Development