Improvements for doc/api/packages.md

There are some improvements we can do for doc/api/packages.md:

• mention the pipeline attribute, which returns the most recent pipeline for the package. Add that, if there aren't any pipelines associated with the package, the pipeline attribute is not included in the response.
• Include the pipeline attribute in list of attributes and in the example JSON response for:
  • https://docs.gitlab.com/ee/api/packages.html#for-a-project
  • https://docs.gitlab.com/ee/api/packages.html#for-a-group
  • https://docs.gitlab.com/ee/api/packages.html#get-a-project-package

This can be useful for developers using the API. After a call to the List project packages endpoint, the developer can first check if the pipeline attribute is present before calling the Get package pipelines endpoint. This will save at least one API call and improve the runtime of pipelines.

added documentation grouppackage registry labels

set weight to 1

added devopspackage sectionci labels

changed title from Minor improvement for doc/api/packages.md to Improvements for doc/api/packages.md

changed the description

mentioned in merge request !150103 (merged)

mentioned in issue gitlab-org/quality/triage-reports#17443 (closed)

mentioned in issue gitlab-org/quality/triage-reports#17610 (closed)

added Category:Package Registry label

changed milestone to %Backlog