Cli: [easy] add .netlify to .gitignore if exists, on `netlify init`

[sw-yx]

- Do you want to request a feature or report a bug?
[easy] add .netlify to .gitignore if exists, on netlify init

- What is the current behavior?

no action

[biilmann]

I don't think we want to ignore the .netlify folder - it's useful that everyone in the same repo get the same site id if doing manual deploys

[DavidWells]

.netlify will likely contain more things in the future (caches, plugin data, etc).

If people want to manually set the ID (which limits the reuse of the repo), they can set that in the netlify.toml file

I’d wager this property is not used very often in Netlify.toml.

I think we should ignore the .netlify folder by default