Add differences section on README

[dense-analysis]

Add differences section on README

[petRUShka]

+1 for placing differences in README. It is really hard to decide what to use in a quick search.

[w0rp]

This plugin checks the text buffer instead of the file on disk, so you can check for problems before a file has been saved.

[w0rp]

I'm not sure that's the kind of message I want to write in the README. I'd rather explain what this plugin does, and let people decide themselves.

[KabbAmine]

Why add it to the README? It's quite easy to spot the differences:

• Neomake is for neovim only (A PR is in work for vim 8).
• Syntastic is synchronous

[nhooyr]

Now that neomake has vim 8 support, what is the difference?

[nhooyr]

That's weird, I'd expect neomake to support that. Ok thanks!

Then take your time!

For now, im sticking with NeoMake! But who knows!

[markstos]

Having a basic mention of the differences in the README would be helpful.

[w0rp]

This kind of thing belongs on a wiki page, not in the README for one of the projects.