Improve IO::Handle abstract.

doc/Type/IO/Handle.pod6

@@ -6,6 +6,16 @@
 
    class IO::Handle { }
 
+
+Instances of C<IO::Handle> encapsulate an I<handle> to manipulate input/output resources.
+Usually there is no need to create directly an C<IO::Handle> instance, since it will be done
+by other roles and methods. For instance, thru the L<IO> role it is possible to get an handle
+to a file that will result of type C<IO::Handle>:
+
+    my $fh = '/tmp/log.txt'.IO.open;
+    say $fh.^name; # OUTPUT: IO::Handle
+
+
 =head1 Methods
 
 =head2 method open