docs: Remove mention of filing issues, since they are disabled in the repository

[anaulin]

The troubleshooting guide talks about filing issues and links to /issues, but this link redirects to /pulls, as this repository does not to have "issues" functionality enabled (or at least it is not visible to me):

This PR removes the line about filing issues, in order to avoid confusion.

If there is a better text to put in its place, let me know or edit the PR directly.