added 6.0.2 warning, preparing new tag 6.0.3

Author: cirpo

README.md

@@ -179,6 +179,8 @@ Added the ability to set custom properties in the header. Moved automatic inclus
 - Dropped support for PHP 5.3
 - Don't escape slashes when generating signin input.
   This may render tokens generated with earlier versions of Jose incompatible.
+- **DON'T** install version 6.0.2! It's using phpseclib version 2 instead of version 1 and some classes are broken
+
 
 ## Credits