remove ineffective X

Author: tbrowder

doc/Language/operators.pod6

@@ -176,7 +176,7 @@ autovivified if possible.  Some examples:
     $a min= 2; # 2
     
     my $s = 'a';
-    $s X<~=> 'b'; # 'ab'
+    $s ~= 'b'; # 'ab'
 
 This behavior is automatically extended to include custom-defined infix operators.