Add link to CI docs in PR template (#287)

Signed-off-by: Marcus Noble <[email protected]>

.github/pull_request_template.md

@@ -8,6 +8,8 @@ If for some reason you want to skip the e2e tests, remove the following line.
 
 Note: Tests are not automatically executed when creating a draft PR
 If you do want to trigger the tests while still in draft then please add a comment with the trigger.
+
+Full docs and all optional params can be found at: https://github.com/giantswarm/cluster-test-suites#%EF%B8%8F-running-tests-in-ci
 -->
 
 /run cluster-test-suites