Add GitHub template for Pull Requests

For all of the those who are willing to contribute via GitHub
add an important notice to say where they should push their
code: Gerrit and NOT GitHub.

Change-Id: I6fa69b4c5cbc293e150ef8a6117d1f22f813e724
diff --git a/PULL_REQUEST_TEMPLATE.md b/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 0000000..19c0f3a
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+++ b/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,7 @@
+# Important Notice
+
+Patch submission and review is done through [Gerrit Code Review](https://gerrit-review.googlesource.com).
+Unfortunately we cannot pull your code as a Pull Request.
+
+__NO REVIEWS OR DISCUSSIONS will happen on GitHub__, all the code collaboration
+will take place on Gerrit.