[gtk+] Update release notes a bit

[Matthias Clasen <matthiasc src gnome org>]

commit 73f1d62b6898e86aa24047e541c4def0243dcd64
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Aug 15 13:40:30 2015 -0400

    Update release notes a bit

 README.in |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)
---
diff --git a/README.in b/README.in
index 173a01c..4ff9b32 100644
--- a/README.in
+++ b/README.in
@@ -73,6 +73,18 @@ Patches should be in unified diff form. (The -up option to GNU diff)
 Even better are git-formatted patches. (Use git format-patch)
 
 
+Release notes for 3.18
+======================
+
+* The GtkListBox model support that was introduced in 3.16 has been
+  changed to no longer call gtk_widget_show_all on rows created by
+  the create_widget_func. You need to manage the visibility of child
+  widgets yourself in your create_widget_func.
+
+* The alpha component of foreground colors that are applied to
+  GtkCellRendererText is no longer ignored. If you don't want your
+  text to be translucent, use opaque colors.
+
 Release notes for 3.16
 ======================
 
@@ -99,7 +111,7 @@ Release notes for 3.16
   has non-scrolling parts similar to treeview headers, there is no need
   to implement this vfunc.
 
-* The GtkSearchEntry widget has gained a number of new signal that
+* The GtkSearchEntry widget has gained a number of new signals that
   are emitted when certain key sequences are seen. In particular, it
   now handles the Escape key and emits ::stop-search. Applications that
   expect to handle Escape themselves will need to be updated.