allows nested repository discovery

[pythys]

A simple fix related to #49 by removing the if/else branch, thus allowing the tool to continue walking the directory tree, find any additional git repositories and register them.

I am working on additional logic to read the contents of .gitmodules if it exists, and then ignore the repositories defined over there since their discovery is the responsibility of git itself, not grm

[hakoerber]

Hey, thank you for your contribution!

I tried it, but unfortunately, recursing unconditionally led to a few problems:

• It will also recurse into gitignored files. As an example, I have a per-project cargo registry cache which is gitignored, but that grm picked up because it's simply a git repository.
• The runtime against my repository tree went from 300ms, to almost 3 seconds, so a tenfold increase. It's no longer instantaneous. This gap will get worse which a bigger repository tree. I guess this will improve with handling of submodules and gitignored files.

So I think this is fine as a first iteration, but not yet ready to be merged. Let me know when you make progress or if you need support!

[pythys]

I will close this and issue another PR later, substantial code needs to go in to handle .gitignore, .gitmodules and so on and so forth.