Adding release notes for 1.2.0 helm charts

Change-Id: I6e0aa8808d5c9264f870176b53a594a3c8719642
diff --git a/index.rst b/index.rst
index 4d93129..5cbc2c6 100644
--- a/index.rst
+++ b/index.rst
@@ -104,3 +104,4 @@
    release/process
    release/1.0.0
    release/1.1.0
+   release/1.2.0