Change link to Gerrit tutorial in PR template

The new tutorial targets GitHub users and it is much shorter than the
other one.

Change-Id: I3c5deb43b0fc756658373e33669ab1b091427a13
diff --git a/.github/ b/.github/
index 4daf3fd..fc66768 100644
--- a/.github/
+++ b/.github/
@@ -8,7 +8,7 @@
   You can learn how to do that in the following document:
-  *
+  *
   If you're not comfortable using Gerrit, you can submit your pull
   request here at GitHub and we'll manually transfer it to Gerrit :)