[gtksourceview] tag: document that GtkTextTag is preferable when sufficient

[Sébastien Wilmet <swilmet src gnome org>]

commit c57bc49cc4488c4cb338a6b903b2de4dad5860c5
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Wed Jun 1 14:19:54 2016 +0200

    tag: document that GtkTextTag is preferable when sufficient

 gtksourceview/gtksourcetag.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gtksourceview/gtksourcetag.c b/gtksourceview/gtksourcetag.c
index b3329f8..ab6c796 100644
--- a/gtksourceview/gtksourcetag.c
+++ b/gtksourceview/gtksourcetag.c
@@ -35,6 +35,9 @@
  *
  * #GtkSourceTag is a subclass of #GtkTextTag that adds properties useful for
  * the GtkSourceView library.
+ *
+ * If, for a certain tag, #GtkTextTag is sufficient, it's better that you create
+ * a #GtkTextTag, not a #GtkSourceTag.
  */
 
 typedef struct _GtkSourceTagPrivate GtkSourceTagPrivate;