Exception output message was fixed

Author: Altai-man

doc/Type/X/TypeCheck/Assignment.pod6

@@ -12,7 +12,7 @@ For example, this will die
 
     my Int $x = "foo";
     CATCH { default { put .^name, ': ', .Str } };
-    # OUTPUT: «X::Assignment::RO: Cannot modify an immutable Any␤»
+    # OUTPUT: «X::TypeCheck::Assignment: Type check failed in assignment to $x; expected Int but got Str ("foo")␤»
 
 though compilers are allowed to detect obvious cases like this example
 and complain at compile time with a different error.