Update README.md

Author: technoblogy

README.md

@@ -4,4 +4,4 @@ A version of the Lisp programming language for ESP8266 and ESP32-based boards.
 The "-comments" version is identical but includes comprehensive comments.
 
 For more information see:
-http://www.ulisp.com/show?21T5
+http://www.ulisp.com/show?3M#esp-version