docs: update developer info

Update piglit link to the current Piglit website.

Add note about updating patchwork when sending patch revisions.

Acked-by: Matt Turner <mattst88@gmail.com>
diff --git a/docs/devinfo.html b/docs/devinfo.html
index 0da18b9..8ebf80f 100644
--- a/docs/devinfo.html
+++ b/docs/devinfo.html
@@ -244,7 +244,7 @@
 
 <p>
 Whenever possible and applicable, test the patch with
-<a href="http://people.freedesktop.org/~nh/piglit/">Piglit</a> to
+<a href="http://piglit.freedesktop.org">Piglit</a> to
 check for regressions.
 </p>
 
@@ -266,6 +266,12 @@
 it harder for reviewers to accidentally review old patches.
 </p>
 
+<p>
+When submitting follow-up patches you should also login to
+<a href="https://patchwork.freedesktop.org">patchwork</a> and change the
+state of your old patches to Superseded.
+</p>
+
 <h3>Reviewing Patches</h3>
 
 <p>