Document IO handle closure in traps

Closes #1365

Author: zoffixznet

doc/Language/traps.pod6

@@ -483,6 +483,21 @@ handy in various instances.
 
 =head1 Input and Output
 
+=head2 Closing Open File Handles and Pipes
+
+Unlike some other languages, Perl 6 does not use reference counting,
+and so B<the file handles are NOT closed when they go out of scope>. You
+have to explicitly close them either by using L<close> routine or using the
+C<:close> argument several of L<IO::Handle's|/type/IO::Handle> methods accept.
+See L«C<IO::Handle.close>|/type/IO::Handle#routine_close» for details.
+
+The same rules apply to L<IO::Handle's|/type/IO::Handle> subclass
+L<IO::Pipe>, which is what you operate on when reading from a L<Proc> you get
+with routines L<run> and L<shell>. 
+
+The caveat applies to L<IO::CatHandle> type as well, though not as severely.
+See L«C<IO::CatHandle.close>|/type/IO::CatHandle#method_close» for details.
+
 =head2 IO::Path Stringification
 
 Partly for historical reasons and partly by design, an L<IO::Path> object