docs(usage): add an example on how to retrieve container images (#141)

Co-authored-by: Dana Alsharif <danaalsharif03@gmail.com>
Co-authored-by: Tibor Šimko <tibor.simko@cern.ch>

AUTHORS.md

@@ -4,10 +4,12 @@ The list of contributors in alphabetical order:
 
 - [Adam Novorolnik](https://github.com/ANovorolnik)
 - [Alex Mieth](https://github.com/AlexMieth)
+- [Dana Alsharif](https://github.com/danaalsharif)
 - [Daniel Prelipcean](https://orcid.org/0000-0002-4855-194X)
 - [Jan Okraska](https://orcid.org/0000-0002-1416-3244)
 - [Jiri Kuncar](https://github.com/jirikuncar)
 - [Joud Masoud](https://github.com/joudmas)
+- [Mohammad Doleh](https://github.com/d0leh)
 - [Pablo Saiz](https://github.com/psaiz)
 - [Parth Shandilya](https://github.com/ParthS007)
 - [Tibor Simko](https://orcid.org/0000-0001-7202-5803)

docs/usage.md

@@ -98,6 +98,18 @@ $ cernopendata-client get-metadata --recid 329 --output-value authors.name --fil
 Rousseau, David
 ```
 
+Another example of using \--filter would be retrieving the container image
+details. For instance, to get the container images registered in Docker Hub
+repository for a specific open data record, you can use:
+
+``` console
+$ cernopendata-client get-metadata --recid 22234 --output-value system_details.container_images.name
+docker.io/cmsopendata/cmssw_7_6_7-slc6_amd64_gcc493:latest
+gitlab-registry.cern.ch/cms-cloud/cmssw-docker-opendata/cmssw_7_6_7-slc6_amd64_gcc493:latest
+$ cernopendata-client get-metadata --recid 22234 --output-value system_details.container_images.name --filter registry=dockerhub
+docker.io/cmsopendata/cmssw_7_6_7-slc6_amd64_gcc493:latest
+```
+
 ## Listing available data files
 
 In order to get a list of data files belonging to a record, please use