Fix typo in the PR template

Author: carusogabriel

docs/PULL_REQUEST_TEMPLATE.md

@@ -8,4 +8,4 @@ Fixes # (issue)
 
 - [ ] I have run `composer run-script check --timeout=0` and no errors were reported
 - [ ] The new code is covered by unit tests (check build/coverage for coverage report)
-- [ ] I have update the documentation to describe the changes
+- [ ] I have updated the documentation to describe the changes