mendel: Update branch to release-chef

Change-Id: I41c087ccb3076bb902400bb4f9ae31f03e0356f8

mendel.xml

diff --git a/mendel.xml b/mendel.xml
index 583dc9f..4581c8d 100644
--- a/mendel.xml
+++ b/mendel.xml
@@ -6,7 +6,7 @@
     <remote fetch="sso://aiyprojects" name="coral-internal"
       review="sso://aiyprojects" />
 
-    <default remote="coral" revision="master" />
+    <default remote="coral" revision="release-chef" />
 
     <project name="docs" path="docs">
       <linkfile src="GettingStarted.md" dest="GettingStarted.md" />