explain how to disambiguate meta ops

Author: gfldex

doc/Language/operators.pod6

@@ -122,8 +122,9 @@ Meta operators can be parameterized with other operators or subroutines in the
 same way as functions can take functions as parameters. To use a subroutine as
 a parameter, prefix its name with a C<&>. Perl 6 will generate the actual
 combined operator in the background, allowing the mechanism to be applied to
-user defined operators. There are quite a few Meta operators with different
-semantics as explained, next.
+user defined operators. To disambiguate chained meta operators enclose the
+inner operator in square brackets. There are quite a few Meta operators with
+different semantics as explained, next.
 
 =head1 Substitution Operators