Improves push-at-least refs #1395

doc/Type/Iterator.pod6

@@ -180,7 +180,13 @@ for $þor -> $first, $second {
 }
 =end code
 
-This code, which groups DNA chains in triplets (usually called I<codons>) returns those codons when requested in a loop; if too many are requested, like in the first case C«for $b -> $a, $b, $c», it simply does not enter the loop since C<push-exactly> will return C<IterationEnd> since it is not able to serve the request for exactly 3 codons. In the second case, however, it requests exactly two codons in each iteration of the loop; C<push-exactly> is being called with the number of loop variables as the C<$count> variable.
+This code, which groups DNA chains in triplets (usually called I<codons>)
+returns those codons when requested in a loop; if too many are requested, like
+in the first case C«for $b -> $a, $b, $c», it simply does not enter the loop
+since C<push-exactly> will return C<IterationEnd> since it is not able to serve
+the request for exactly 3 codons. In the second case, however, it requests
+exactly two codons in each iteration of the loop; C<push-exactly> is being
+called with the number of loop variables as the C<$count> variable.
 
 =head2 method push-at-least
 
@@ -203,7 +209,12 @@ produce more elements to achieve better performance.
     say (1 .. ∞).iterator.push-at-least(@array, 10); # OUTPUT: «10␤»
     say @array; # OUTPUT: «[1 2 3 4 5 6 7 8 9 10]␤»
 
-The Iterator role implements this method in terms of C<pull-one>.
+The Iterator role implements this method in terms of C<pull-one>. In general, it
+is also not intended to be called directly as in the example above. It can be
+implemented, if unhappy with this default implementation, by those using this
+role. See
+L<the documentation for C<push-exactly>|https://docs.perl6.org/type/Iterator#method_push-exactly>
+for an example implementation.
 
 =head2 method push-all