Modify example to show explicit cloning vs binding

Example previously mentions the pitfalls of implicit binding when
creating a Pair and suggests cloning. Now shows cloning explicitly.

Author: jstuder-gh

doc/Language/variables.pod6

@@ -630,13 +630,17 @@ Many operators come with implicit binding which can lead to actions at a distanc
 Use C<.clone> or coercion to create a new container that can be bound to.
 
     my @a;
+    my @a-cloned;
     sub f() {
         state $i;
         $i++;
-        @a.push: "k$i" => $i # <-- .clone goes here
+        @a\      .push: "k$i" => $i;
+        @a-cloned.push: "k$i" => $i.clone;
     };
+
     f for 1..3;
-    dd @a; # OUTPUT: «Array @a = [:k1(3), :k2(3), :k3(3)]␤»
+    say @a;        # OUTPUT: «[k1 => 3 k2 => 3 k3 => 3]␤»
+    say @a-cloned; # OUTPUT: «[k1 => 1 k2 => 2 k3 => 3]␤»
 
 State variables are shared between all threads. The result can be unexpected.