Question: `git mv` renames a file or directory in a repository. How do I rename the Git repository itself?

Answer: 
Rename `PRJ0.git` to `PROJ1.git`, then edit the URL variable located in the `.git/config` file of your project.
It's ambiguous what you mean by "renaming a git repository itself", but one interpretation of that is changing the URL of a remote git repository.

```
git remote set-url origin url

```

<https://www.commands.dev/workflows/change_url_of_remote_git_repository>

I bookmarked ^ page, it tells me the command and allows me play around with the parameters. Super useful, IMO.