docs: update calendar, add news and link release notes to 18.0.1

Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com>
diff --git a/docs/index.html b/docs/index.html
index 7de6845..2383d98 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -18,6 +18,12 @@
 
 <h2>April 18, 2018</h2>
 <p>
+<a href="relnotes/18.0.1.html">Mesa 18.0.1</a> is released.
+This is a bug-fix release.
+</p>
+
+<h2>April 18, 2018</h2>
+<p>
 <a href="relnotes/17.3.9.html">Mesa 17.3.9</a> is released.
 This is a bug-fix release.
 <br>