Better document per-host configuration

action items: https://github.com/cli/cli/issues/1980#issuecomment-702258545

---

original issue:

Whenever I try to clone a repo I get:
```
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
exit status 128
```

I want to change so it clones using https but I dont know how to change it. The "git_protocol" setting it set as https so I don't even know why i tries to use ssh...

Repository is public.