Log warning in case of 404 for unrecognized route

[Gregor Martynus]

follow up to #80 (comment)

The setup would work similar to how https://github.com/octokit/plugin-paginate-rest.js updates src/generated/paginating-endpoints.ts.

1. Create an update workflow like octokit/plugin-paginate-rest.js:.github/workflows/update.ym
2. Create an update-endpoints script that will take the OpenAPI specification from @octokit/openapi, create/update a generated/rest-api-routes.js file, which would be an array of all REST API routes that GitHub supports
3. When sending a request, compare the given route to the known routes defined in generated/rest-api-routes.js. If the route is unknown, log a warning if the response is a 404.

No worries if that doesn't make sense @praneetloke, there is lots of inside knowledge behind how the automated updates work for the@octokit/* packages based updates to GitHub's OpenAPI specifications