[gtk-doc] Add new flavours to the help output.

[Stefan Sauer <stefkost src gnome org>]

commit 39a94bd61aa9d034e507c5ee13b1b6f670930891
Author: Stefan Sauer <ensonic users sf net>
Date:   Thu Feb 14 21:07:54 2019 +0100

    Add new flavours to the help output.

 buildsystems/autotools/gtkdocize.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/buildsystems/autotools/gtkdocize.in b/buildsystems/autotools/gtkdocize.in
index 048005e..83127bf 100755
--- a/buildsystems/autotools/gtkdocize.in
+++ b/buildsystems/autotools/gtkdocize.in
@@ -17,7 +17,7 @@ flavour=no-tmpl
 
 # mini help
 usage="\
-usage: $progname [ --copy ] [ --docdir DIR ] [ --flavour {legacy|legacy-flat|no-tmpl|no-tmpl-flat} ] [ 
--srcdir DIR ]"
+usage: $progname [ --copy ] [ --docdir DIR ] [ --flavour 
{legacy|legacy-flat|no-tmpl|no-tmpl-flat|no-xslt|no-xslt-flat} ] [ --srcdir DIR ]"
 
 # Find the srcdir early (and ignore a srcdir set in configure).
 # https://bugzilla.gnome.org/show_bug.cgi?id=707426