[io grant] Use idiomatic Perl 6 in example

Author: zoffixznet

doc/Type/IO.pod6

@@ -296,11 +296,8 @@ is C<False>, implying text semantics.
 
 The encoding to use if opened in text mode.
 
-    # open explicitly as utf8
-    my $fh = open("path-to-file", enc => "utf8");
-    my $fh = open("path-to-file", enc => "utf-8");  # this form also works
-    # open with latin1 encoding
-    my $fh = open("path-to-file", enc => "latin1");
+    my $fh1 = open 'path-to-file';                # default, utf-8
+    my $fh2 = open 'path-to-file', :enc<latin-1>; # explicit, latin-1
 
 Defaults to C<utf8>. The values are case-insensitive. The available encodings
 vary by implementation and backend. On Rakudo MoarVM the following are