Insights: add the read:issues permission

[c-brooks]

Why:

cc/ https://github.com/github/insights/issues/2024
cc/ @github/insights

There was recently a change to Insights so the GitHub App needs additional permissions, and we need to update the Docs so that customers know to add the read:issues permissions to their apps.

What's being changed:

1. Adds instructions to add the read:issues permissions to the initial GH App creation:

2. Adds a section to upgrade from Insights v1.5.0-alpha.1

Check off the following:

• I have reviewed my changes in staging. (look for the deploy-to-heroku link in your pull request, then click View deployment)
• For content changes, I have reviewed the localization checklist
• For content changes, I have reviewed the Content style guide for GitHub Docs.

[welcome]

Thanks for opening this pull request! A GitHub docs team member should be by to give feedback soon. In the meantime, please check out the contributing guidelines.

[janiceilene]

Thanks @c-brooks! I'll get this triaged for the team to review ⚡

[c-brooks]

@janiceilene Is it possible to get this reviewed today? We’d like to put it out today with our release. thanks!

[vanobig]

🐑 it

[lecoursen]

👋🏻 @c-brooks, can you open an issue about this in the private repo? This update will require a bit more discussion. Thanks!

[github-actions]

This PR is stale because it has been open 7 days with no activity and will be automatically closed in 3 days. To keep this PR open, update the PR by adding a comment or pushing a commit.

[janiceilene]

It looks like this was moved to an internal issue, so I'm going to close this up ⚡