[gnome-software] trivial: Fix up a gtk-doc comment

[Richard Hughes <rhughes src gnome org>]

commit 7bc7f3220078eb08914fa4ad7bd444281e6df773
Author: Richard Hughes <richard hughsie com>
Date:   Wed Jun 1 13:36:11 2016 +0100

    trivial: Fix up a gtk-doc comment

 src/gs-category.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)
---
diff --git a/src/gs-category.c b/src/gs-category.c
index b2efabf..984c92c 100644
--- a/src/gs-category.c
+++ b/src/gs-category.c
@@ -256,9 +256,7 @@ gs_category_get_key_colors (GsCategory *category)
  * @category: a #GsCategory
  * @key_color: a #GdkRGBA
  *
- * Adds a key color to the category icon.
- *
- * Returns: the string, or %NULL
+ * Adds a key color to the category.
  **/
 void
 gs_category_add_key_color (GsCategory *category, const GdkRGBA *key_color)