[gimp] app: update documentation comment of gimp_guide_custom_new().

[Jehan Pagès <jehanp src gnome org>]

commit 7364c37158b2bbecdf8886e5a6a3cfffa5982b2a
Author: Jehan <jehan girinstud io>
Date:   Thu Feb 11 17:40:45 2016 +0100

    app: update documentation comment of gimp_guide_custom_new().
    
    Say in the doc that custom guides do not follow snapping settings.

 app/core/gimpguide.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/app/core/gimpguide.c b/app/core/gimpguide.c
index e6a1b10..8b9eaa0 100644
--- a/app/core/gimpguide.c
+++ b/app/core/gimpguide.c
@@ -209,6 +209,7 @@ gimp_guide_new (GimpOrientationType  orientation,
  * drive GEGL ops, etc.
  * They are not saved in the XCF file. If an op, a symmetry or a plugin
  * wishes to save its state, it has to do it internally.
+ * Moreover they don't follow guide snapping settings and never snap.
  *
  * Returns: the custom #GimpGuide.
  **/