Add documentation for jobs keyset pagination

What does this MR do and why?

Since Jobs API now supports keyset pagination, we should have the document available to the public

Screenshots or screen recordings

How to set up and validate locally

https://main-ee-109030.docs.gitlab-review.app/ee/api/jobs.html#list-project-jobs

https://main-ee-109030.docs.gitlab-review.app/ee/api/rest/index.html#keyset-based-pagination

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #385940 (closed)