GitLab for Jira app: Add instructions/guidance step to self-managed setup flow

Description

During the installation flow for the GitLab for Jira app, there are many manual steps required by users that may be challenging. Until we are able to automate and improve the UX for this flow (in a future follow-up), we want to supply additional context to users going through this process.

At minimum, this should include a link to our docs with some explanation or high level steps.

https://docs.gitlab.com/ee/integration/jira/connect-app.html#connect-the-gitlabcom-for-jira-cloud-app-for-self-managed-instances

Ideally, we could embed a video walkthrough showing users how to complete the setup.

Design

See wireframes in Figma.