Add Contrast variant

[azemoh]

Add a Contrasted variant of the theme with a darker background.
See #30

[waldyrious]

@azemoh would such a contrast version live in this repository? Could you provide some pointers to beginner-friendly documentation, and examples of multi-theme repositories that you consider well organized, for people who never authored a theme from scratch?

[Jawkel]

In your settings.json, you can add :
"workbench.colorCustomizations": { "[One Monokai]": { "editor.background": "#1d2225" } }
Pick whatever color suits you best.