Change links to documentation

.github/pull_request_template.md

@@ -1,8 +1 @@
-Before to submit your pull-request:
-
-- Be sure that the unit tests pass
-- If you create a new feature, test your code, and do not introduce new bugs
-- Avoid code duplication
-- Remember, small pull-requests are easier to review and can be merged quickly
-- 1 pull-request == 1 feature/improvement
-- Nonessential features should be implemented as plugin
+[] I read the [contributor guidelines](https://docs.kanboard.org/en/latest/developer_guide/contributing.html#i-want-to-contribute-to-the-code)