Colors work only with termguicolors option enabled

[homedirectory]

I just installed neogit and encountered an issue of lacking any colors whatsoever. Spent some time investigating it, and found out that Neogit* highlight groups define only guifg and guibg but completely ignore ctermfg and ctermbg, hence no colors for users who have option termguicolors disabled.
I think it would be helpful to mention this in the README and in the documentation, that is, that termguicolors must be enabled.