Fix a comment that indicates what "say @array" will print.

We assigned 6 to @array[1] a few lines before, so say @array will print
"a 6 b", not "a 2 b".

perl6.html.markdown

@@ -64,7 +64,7 @@ say "Interpolate an array using [] : @array[]";
 
 my @keys = 0, 2;
 @array[@keys] = @letters; # Assign using an array
-say @array; #=> a 2 b
+say @array; #=> a 6 b
 
 # There are two more kinds of lists: Parcel and Arrays.
 # Parcels are immutable lists (you can't modify a list that's not assigned).