Check out the following Blog post on the integration for more details, but as covered in the blog you will want to Install the GitHub app to set up the integration:
Using the old GitHub integration?
The legacy ability to connect Jira Software and GitHub via the Jira DVCS connector is now deprecated in favor of this new GitHub-maintained integration. Note: GitHub Enterprise customers who are using the DVCS Connector will be unaffected at this time. Stay tuned for updates on an upcoming Jira Software and GitHub Enterprise integration.
Yes, if you're using GIThub's cloud deployment, github.com, for your repos, with the caveat mentioned in the article I linked about the new connector requirement, over the legacy connector.
This app officially supports GitHub.com and Jira Cloud. Support for GitHub Enterprise and/or Jira server may be considered in the future.
Covered in the article, with some screenshots of the behavior for referance, when using the new connector in Next gen projects the development details are viewed in the issue card on the dashboard view.