Add contributing guide to setup dev environment

[staticf0x]

This was prompted by #216 and I wanted to document how to get started first, because for me at least it was the biggest obstacle (not necessarily because of python-lsp-server itself, but the cooperation with sublime text too). However, I quickly got into troubles as I didn't know what kind of information this guide could and should contain. Not sure if I'll be able to create something good enough without deeper knowledge of pylsp.

[staticf0x]

@ccordoba12 Could you advise what info would be important to have in a contributing guide?

[pkulev]

I like it, thanks!

[ccordoba12]

Thanks for your contribution @staticf0x! I left a discussion comment for you below.

[ccordoba12]

I don't know if mentioning one preferred editor over others is a good idea because the setup and development workflow is completely different for each of them. I mean, I could write a guide for Spyder as well (which would be useful for our interested contributors) and it'd be another thing entirely.

So, perhaps having a contributing guide per editor would be better?

[staticf0x]

I understand, I initially mentioned ST4 because making it use a custom pylsp path was very difficult, so I felt it was important. But yes, there's too many editors and IDEs to cover that it might not be a good idea to have it in the contributing guide.

So, perhaps having a contributing guide per editor would be better?

That sounds like a good idea.

[doolio]

So, perhaps having a contributing guide per editor would be better?

That sounds like a good idea.

Or perhaps none at all? Surely, those who are able and willing to contribute will be able to configure their editor already.

[staticf0x]

Removed the ST config in favor of a generic point of configuring the editor.

[ccordoba12]

Last suggestions for you @staticf0x, then this should be ready.

[staticf0x]

Done, thanks

[ccordoba12]

Looks good to me now, thanks @staticf0x!