Improve behavior of :NullLsInfo

[filipekiss]

First of all, thank for all the hard work you put in this plugin. It really saves a lot of time when trying to configure non-LSP sources.

I was first setting up the plugin and I did a simple call to require('null-ls').setup() and things worked as expected (as in I got no errors).

I understand that, by default, NullLs doesn't attach to the buffers, which makes sense, but, at the same time, it renders the command a little bit useless.

So I was thinking that maybe the command :NullLsInfo could be improved in a way that, by default, if no sources are configured for the current buffer, it would detect the filetype and show me the available sources from the builtins.

That way, I can open a file for a language and run :NullLsInfo and I'll have a list of all available sources that I can use, making discoverability for builtins a lot better.

I haven't looked at the source code yet so I'm not sure how difficult it would be to implement something like this, but I think it would greatly improve the overall experience of using and configuring NullLs, especially for new comers.

Once again, thanks for all your hard work and let me know if I can help in any way :)

[lehmacdj]

Are you sure you successfully setup null-ls? When I have only require('null-ls').setup() the :NullLsInfo command is still defined, and I can do exactly what you suggest and with my actual config I can still do it for filetypes where I don't have anything configured.

[jose-elias-alvarez]

The functionality described was added in #671.