Update release notes, adding howto pages for documenting individual release activities

Change-Id: I2fb29c4ed4467126bfcdaa097b1dd8329ce7adfe
diff --git a/howto/release/index.rst b/howto/release/index.rst
index 06b7d39..4d28d04 100644
--- a/howto/release/index.rst
+++ b/howto/release/index.rst
@@ -23,5 +23,7 @@
    voltctl/see_also
 
    checklist
+   repositories/index
    scripts/preparation
    scripts/repository-voltha-release
+   voltha-system-tests/index