docs: update calendar, add news item and link release notes for 17.1.3

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
diff --git a/docs/index.html b/docs/index.html
index 9fc9957..db4c570 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -16,6 +16,12 @@
 
 <h1>News</h1>
 
+<h2>June 19, 2017</h2>
+<p>
+<a href="relnotes/17.1.3.html">Mesa 17.1.3</a> is released.
+This is a bug-fix release.
+</p>
+
 <h2>June 5, 2017</h2>
 <p>
 <a href="relnotes/17.1.2.html">Mesa 17.1.2</a> is released.