[1.x] Clarifies serialization on REPL environments

Author: nunomaduro

README.md

@@ -53,6 +53,7 @@ echo $closure(); // james;
 
 1. Creating **anonymous classes** within closures is not supported.
 2. Using attributes within closures is not supported.
+3. Serializing closures on REPL environments - such as Laravel Tinker - is not supported.
 
 ## Contributing