Add ranger example in README

[Bruno Heridet]

Hello

Now that ranger is gone from the "official" rc in mawww/kakoune@f38152d I assume many newcomers will now try to use connect.kak

The README already have examples for lf and fzf which is great!
We could add another explicit line with a ranger example, this way new users will feel reassured that connect.kak also works with ranger if they don't know (yet) that lf is a ranger-like program.

[Taupiqueur]

Yoo. I replaced the lf example with ranger.

[Taupiqueur]

You are not very active these days. Hope you’re good.