[glib/sam/use-g-define-quark] Update GError docs to use G_DEFINE_QUARK

[Sam Thursfield <sthursfield src gnome org>]

commit f9b65c01bf9d1c5a5e6c9d0af08f1efbff529033
Author: Sam Thursfield <sam afuera me uk>
Date:   Wed Feb 26 20:01:10 2020 +0100

    Update GError docs to use G_DEFINE_QUARK

 glib/gerror.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)
---
diff --git a/glib/gerror.c b/glib/gerror.c
index cf20bc8c0..0e99f0e2a 100644
--- a/glib/gerror.c
+++ b/glib/gerror.c
@@ -264,11 +264,7 @@
  *   |[<!-- language="C" -->
  *   #define G_SPAWN_ERROR g_spawn_error_quark ()
  *
- *   GQuark
- *   g_spawn_error_quark (void)
- *   {
- *       return g_quark_from_static_string ("g-spawn-error-quark");
- *   }
+ *   G_DEFINE_QUARK (g-spawn-error-quark, g_spawn_error);
  *   ]|
  *
  * - The quark function for the error domain is called