Link to documentation in Jira app

What does this MR do?

It adds a documentation link to the Jira app descriptor. This link should show up in our application in the Atlassian Marketplace.

Originally I wanted to fix the supported option as requested in #223943 (closed) but it was already fixed in the application settings. In the docs I found the option to add links and I thought this would be helpful as well.

It produces the following JSON:

{
   "name":"GitLab for Jira (127.0.0.1)",
   "description":"Integrate commits, branches and merge requests from GitLab into Jira",
   "key":"gitlab-jira-connect-127.0.0.1",
   "baseUrl":"https://127.0.0.1:3000/-/jira_connect",
   "lifecycle":{
      "installed":"/events/installed",
      "uninstalled":"/events/uninstalled"
   },
   "vendor":{
      "name":"GitLab",
      "url":"https://gitlab.com"
   },
   "links":{
      "documentation":"https://docs.gitlab.com/ee/integration/jira_development_panel.html#gitlabcom-1"
   },
   "authentication":{
      "type":"jwt"
   },
   "scopes":[
      "READ",
      "WRITE",
      "DELETE"
   ],
   "apiVersion":1,
   "modules":{
      "jiraDevelopmentTool":{
         "key":"gitlab-development-tool",
         "application":{
            "value":"GitLab"
         },
         "name":{
            "value":"GitLab"
         },
         "url":"https://gitlab.com",
         "logoUrl":"http://127.0.0.1:3000/assets/gitlab_logo-7ae504fe4f68fdebb3c2034e36621930cd36ea87924c11ff65dbcb8ed50dca58.png",
         "capabilities":[
            "branch",
            "commit",
            "pull_request"
         ]
      },
      "postInstallPage":{
         "key":"gitlab-configuration",
         "name":{
            "value":"GitLab Configuration"
         },
         "url":"/subscriptions"
      }
   },
   "apiMigrations":{
      "gdpr":true
   }
}

I ran this in the Atlassian Connect Validator and it appears to be valid

How to test on staging

Go to (https://staging.gitlab.com/-/jira_connect/app_descriptor)[https://staging.gitlab.com/-/jira_connect/app_descriptor] and check if the documentation link is included.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• [-] Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team