Add PRdoc check (#1408)

* Add test prdoc
* Prepare for the check
* Escape PR number
* Fix conditional step
* Add checkout and actual check
* Cleanup
* Minor fixes
* Add doumentation
* Add more doc

cumulus/scripts/ci/changelog/README.md

@@ -61,7 +61,7 @@ all the labels that are used, search for `meta` in the templates. Currently, the
 Note that labels with the same letter are mutually exclusive. A PR should not have both `B0` and `B5`, or both `C1` and
 `C9`. In case of conflicts, the template will decide which label will be considered.
 
-## Dev and debuggin
+## Dev and debugging
 
 ### Hot Reload