docs: remove previews - Githubissues

Followup to https://github.com/octokit/endpoint.js/pull/382#issuecomment-1370197900 Requirements:

[ ] https://github.com/octokit/endpoint.js/pull/388
[ ] https://github.com/octokit/core.js/pull/538
[ ] https://github.com/octokit/plugin-paginate-rest.js/pull/486
[ ] https://github.com/octokit/types.ts/pull/491

Behavior

Before the change?

Previews were documented

After the change?

Previews are no longer documented

Other information

This PR must be merged after all other ones in the Octokit JS repos

Additional info

Pull request checklist

[ ] Tests for the changes have been added (for bug fixes / features)
[ ] Docs have been reviewed and added / updated if needed (for bug fixes / features)
[ ] Added the appropriate label for the given change

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

[x] Yes (Please add the Type: Breaking change label)
[ ] No

If Yes, what's the impact:

Removal of previews

Pull request type

Please add the corresponding label for change this PR introduces: - Bugfix: `Type: Bug` - Feature/model/API additions: `Type: Feature` - Updates to docs or samples: `Type: Documentation` - Dependencies/code cleanup: `Type: Maintenance` ----

octokit / octokit.js

docs: remove previews #2372