Correct note about file handles

Resolves #1561.

Author: AlexDaniel

doc/Type/IO/Handle.pod6

@@ -87,15 +87,18 @@ In B<6.d> language, path C<'-'> has no special meaning.
 The C<:out-buffer> controls output buffering and by default behaves as if
 it were C<Nil>. See method L<out-buffer> for details.
 
-B<Note:> unlike some other languages, Perl 6 does not use reference counting,
-and so B<the file handles are NOT flushed or closed when they go out of scope>.
+B<Note (Rakudo versions before 2017.09):>
+B<File handles are NOT flushed or closed when they go out of scope>.
 While they I<will> get closed when garbage collected, garbage collection isn't
 guaranteed to get run. This means I<you should> use an explicit C<close> on
 handles opened for writing, to avoid data loss, and
 an explicit C<close> is I<recommended> on handles opened for reading as well, so
 that your program does not open too many files at the same time, triggering
 exceptions on further C<open> calls.
 
+B<Note (Rakudo versions 2017.09 and after):> Open file handles are
+automatically closed on program exit.
+
 =head2 method comb
 
 Defined as: