docs(changelog): changelog for lts-v2.8.7 release

Signed-off-by: Okash Khawaja <okash@google.com>
Change-Id: I1332b91326e344da403055a1e8d344f0725a281f
diff --git a/Makefile b/Makefile
index 6fe6331..3aa8bb8 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,7 @@
 #
 VERSION_MAJOR			:= 2
 VERSION_MINOR			:= 8
-VERSION_PATCH			:= 6
+VERSION_PATCH			:= 7
 VERSION				:= ${VERSION_MAJOR}.${VERSION_MINOR}.${VERSION_PATCH}
 
 # Default goal is build all images