Add releasenotes page for v0.3.0

This PS is to add releasenotes page for v0.3.0 (current) release
of Patrole.

Change-Id: I7a4701143407dafb818a1ceb573119ebc2cb0365
diff --git a/releasenotes/source/index.rst b/releasenotes/source/index.rst
index 8c90aae..ce29994 100644
--- a/releasenotes/source/index.rst
+++ b/releasenotes/source/index.rst
@@ -6,5 +6,6 @@
    :maxdepth: 1
 
    unreleased
+   v0.3.0
    v0.2.0
    v0.1.0