chore: update PR template (#1863)

Signed-off-by: Diana Lau <[email protected]>

Author: dhmlau

.github/PULL_REQUEST_TEMPLATE.md

@@ -10,8 +10,7 @@ See also #23
 
 ## Checklist
 
-👉 [How to sign off your commits with DCO](https://github.com/strongloop/loopback-datasource-juggler#contributing) 👈
-
+- [ ] [Sign off your commits](https://loopback.io/doc/en/contrib/code-contrib.html) with DCO (Developer Certificate of Origin)
 - [ ] `npm test` passes on your machine
 - [ ] New tests added or existing tests modified to cover all changes
 - [ ] Code conforms with the [style guide](https://loopback.io/doc/en/contrib/style-guide-es6.html)