Coveralls won't comment or set status on PR if repository has not yet been configured

Hi all,

I just ran into an issue where Coveralls won't add comments or set the pull request status on a brand new repository.

To reproduce this issue, create a public Github repository, push some code to it, create a PR, push some trivial changes to it, then run this action without first adding the repository on https://coveralls.io.

Coveralls will gather coverage just fine, but won't update the pull request.

I have added a demonstration of this at https://github.com/ThePadawan/coveralls-action-demo/pull/1 .

The issue can be solved by adding yourself as the repository owner on https://coveralls.io, but this is currently not mentioned anywhere.

I have linked a PR that adds a troubleshooting section for this. I would be glad if you could merge it (after moving the static image asset!) to save other users the same trouble I had debugging this issue.

Cheers!

Review the existing project documentation and the linked demonstration PR to understand where the troubleshooting guidance belongs. Add a troubleshooting section explaining that new repositories must first be added by their owner on Coveralls, and move the static image asset as noted; the documentation should cover the setup needed for comments and pull-request status updates.