Update iterating.pod6

typo: 'a' before 'uniform'

doc/Language/iterating.pod6

@@ -7,7 +7,7 @@
 =head1 The C<Iterator> and C<Iterable> roles
 
 Perl 6 is a functional language, but functions need something to hold on to when
-working on complex data structures. In particular, they need an uniform
+working on complex data structures. In particular, they need a uniform
 interface that can be applied to all of them. This interface is provided by the
 L<Iterator> and L<Iterable> roles.