Adds example addresses https://www.nntp.perl.org/group/perl.perl6.users/2018/06/msg5056.html with @lizmat's example

Author: JJ

doc/Language/objects.pod6

@@ -993,10 +993,16 @@ anonymous roles are supported.
 Note that the object got the role mixed in, not the object's class or the
 container. Thus, @-sigiled containers will require binding to make the role
 stick as is shown in the example with C<@positional>. Some operators will return
-a new value, which effectively strips the mixin from the result.
+a new value, which effectively strips the mixin from the result. That is why it
+might be more clear to mix in the role in the declaration of the variable using
+C<does>:
 
-The operator infix:<but> is narrower than the list constructor. When providing
-a list of roles to mix in, always use parentheses.
+    role R {};
+    my @positional does R = <a b>;
+    say @positional.^name; # OUTPUT: «Array+{R}␤»
+
+The operator C<infix:<but>> is narrower than the list constructor. When
+providing a list of roles to mix in, always use parentheses.
 
 =for code
 role R1 { method m {} }