fix: re-disable in buffers where b:completion is false

[b0o]

Fixes logic from #574 for when b:completion is false. Also updated example configuration in README.md.

[Saghen]

I ought to have looked more carefully, sorry about that. Would this be functionally equivalent to the original code? return vim.bo.buftype ~= 'prompt' and vim.b.completion ~= false

[Saghen]

Reverted the commit on main, thanks!

[b0o]

Ah, you're right. I'm not sure why @soifou was experiencing the issue, as the original logic does seem correct (tested in a prompt buffer and a b:completion = false buffer).

[soifou]

I'm sorry guys, I mixed up 'nofile' and 'prompt' buffers... I was suprised that editing a DressingInput trigger the completion list.