Add .gitignore generator

[Turgon-Aran-Gondolin]

I think gi in your list hasn't updated in a while and .gitignore generator is on the market now. It supports multiple languages/options which gi doesn't (the developer of gi said he's waiting for vscode to update api but I think that's a long time ago and api shouldn't be a problem now). Can you consider adding .gitignore generator?