Update PULL_REQUEST_TEMPLATE.md

.github/PULL_REQUEST_TEMPLATE.md

@@ -23,7 +23,8 @@
 <!--- If you're unsure about any of these, don't hesitate to ask. We're here to help! -->
 - [ ] My code follows the code style of this project.
 - [ ] My change requires a change to the documentation.
-- [ ] I have signed-off my commits with `git commit -s`
 - [ ] I have updated the documentation accordingly.
+- [ ] I've read the [CONTRIBUTION](https://github.com/alexellis/faas/blob/master/CONTRIBUTING.md) guide
+- [ ] I have signed-off my commits with `git commit -s`
 - [ ] I have added tests to cover my changes.
 - [ ] All new and existing tests passed.