Add more context for onos builds

Change-Id: I541d09529471059bab4fad323e16f1505ef57f54
diff --git a/howto/release/components/mcast/index.rst b/howto/release/components/mcast/index.rst
new file mode 100644
index 0000000..a8243a1
--- /dev/null
+++ b/howto/release/components/mcast/index.rst
@@ -0,0 +1,8 @@
+ONOS Component: mcast
+=====================
+
+Dependencies (pom.xml)
+----------------------
+
+- sadis
+