Fix ordering of 2.9.x releases in the release notes index.

Change-Id: Ifd835e4a344710d635caaedc323977d6fbfca8fd

ReleaseNotes/index.txt

diff --git a/ReleaseNotes/index.txt b/ReleaseNotes/index.txt
index 8e7cac6..0b9b611 100644
--- a/ReleaseNotes/index.txt
+++ b/ReleaseNotes/index.txt
@@ -4,8 +4,8 @@
 [[2_9]]
 Version 2.9.x
 -------------
-* link:ReleaseNotes-2.9.html[2.9]
 * link:ReleaseNotes-2.9.1.html[2.9.1]
+* link:ReleaseNotes-2.9.html[2.9]
 
 [[2_8]]
 Version 2.8.x