feature request: custom config file path

[pliski]

Expected behaviour

I would like a CLI option to load another config file instead of the default .tldrrc

Actual behaviour

Only the config file ~/.tldrrc is admitted.

Notes

Actually, as I needed this feature, I already implemented it in my fork: https://github.com/pliski/tldr-node-client.
Sorry for bypassing the preliminary discussion.
I'm submitting a PR for convenience.