Update gitconfig.symlink.example

Added alias for `git` so you can fatthumb `git git <command>` and it'll still work! :)

Before: 

```bash
$ git git status
WARNING: You called a Git command named 'git', which does not exist.
```

After:
```bash
$ git git status
# On branch master
nothing to commit, working directory clean
```

It's recursive so if somehow you manage to type it multiple times, it still works!

```bash
$ git git git git git git git git git status
# On branch status
nothing to commit, working directory clean
```

I learnt it from this Coderwall post https://coderwall.com/p/gx8jrg