Mention 2.8.6.1 in 2.9 release notes

Change-Id: Iae98c892a7ea9192636d0dde5383637f807abd46

ReleaseNotes/ReleaseNotes-2.9.txt

diff --git a/ReleaseNotes/ReleaseNotes-2.9.txt b/ReleaseNotes/ReleaseNotes-2.9.txt
index e74875d..2b5db3d 100644
--- a/ReleaseNotes/ReleaseNotes-2.9.txt
+++ b/ReleaseNotes/ReleaseNotes-2.9.txt
@@ -15,8 +15,9 @@
 link:ReleaseNotes-2.8.2.html[Gerrit 2.8.2],
 link:ReleaseNotes-2.8.3.html[Gerrit 2.8.3],
 link:ReleaseNotes-2.8.4.html[Gerrit 2.8.4],
-link:ReleaseNotes-2.8.5.html[Gerrit 2.8.5], and
-link:ReleaseNotes-2.8.6.html[Gerrit 2.8.6].
+link:ReleaseNotes-2.8.5.html[Gerrit 2.8.5],
+link:ReleaseNotes-2.8.6.html[Gerrit 2.8.6] and
+link:ReleaseNotes-2.8.6.1.html[Gerrit 2.8.6.1].
 These bug fixes are *not* listed in these release notes.
 
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