Added doc for the :close adverb in slurp-rest

Author: Jan-Olof Hendig

doc/Type/IO/Handle.pod6

@@ -208,13 +208,20 @@ Return the current position of the file pointer in bytes.
 
 =head2 method slurp-rest
 
-    multi method slurp-rest(IO::Handle:D: :$bin! --> Buf)
-    multi method slurp-rest(IO::Handle:D: :$enc --> Str)
+    multi method slurp-rest(IO::Handle:D: :$bin!, :$close --> Buf)
+    multi method slurp-rest(IO::Handle:D: :$enc, :$close --> Str)
 
-Return the remaining content of the file from the current file position
+Returns the remaining content of the file from the current file position
 (which may have been set by previous reads or by C<seek>.)  If the
 adverb C<:bin> is provided a L<Buf> will be returned,
-otherwise the return will be a C<Str> with the optional encoding C<:enc>.
+otherwise the return value will be a C<Str> with the optional encoding C<:enc>.
+Specifying the adverb C<:close> will cause the filehandle to be closed when
+the call has finished.
+
+=for code :skip-test
+my $fh = open("content.txt");
+my $line = $fh.get;
+my $rest-of-file = $fh.slurp-rest(:close);
 
 =head2 method Supply