Added a note in the documentation

docs/contributing/packages.md

@@ -13,3 +13,20 @@ make build/somestack-notebook
 4. [Submit a pull request](https://github.com/PointCloudLibrary/pcl/wiki/A-step-by-step-guide-on-preparing-and-submitting-a-pull-request) (PR) with your changes.
 5. Watch for Travis to report a build success or failure for your PR on GitHub.
 6. Discuss changes with the maintainers and address any build issues. Version conflicts are the most common problem. You may need to upgrade additional packages to fix build failures.
+
+## Notes
+
+In order to help identifying packages that can be updated you can use the following helper tool.
+It will list all the packages installed in the `Dockerfile` that can be updated -- dependencies are filtered to focus only on requested packages.
+
+```bash
+$ make check-outdated/base-notebook
+
+# INFO     test_outdated:test_outdated.py:80 3/8 (38%) packages could be updated
+# INFO     test_outdated:test_outdated.py:82 
+# Package     Current    Newest
+# ----------  ---------  --------
+# conda       4.7.12     4.8.2
+# jupyterlab  1.2.5      2.0.0
+# python      3.7.4      3.8.2
+```

pytest.ini

 [pytest]
-addopts = -rA
+addopts = -ra
 log_cli = 1
 log_cli_level = INFO
 log_cli_format = %(asctime)s [%(levelname)8s] %(message)s (%(filename)s:%(lineno)s)