Add nvim-lsp support (#198)

Added highlighting support for the build-in Neovim language server [1] using the coc.nvim [2] groups as reference. 

[1]: https://github.com/neovim/nvim-lsp
[2]: https://github.com/neoclide/coc.nvim

colors/nord.vim

@@ -566,6 +566,14 @@ call s:hi("CocErrorSign" , s:nord11_gui, "", s:nord11_term, "", "", "")
 call s:hi("CocInfoSign" , s:nord8_gui, "", s:nord8_term, "", "", "")
 call s:hi("CocHintSign" , s:nord10_gui, "", s:nord10_term, "", "", "")
 
+" Nvim LSP
+" > neovim/nvim-lsp
+call s:hi("LSPDiagnosticsWarning", s:nord13_gui, "", s:nord13_term, "", "", "")
+call s:hi("LSPDiagnosticsError" , s:nord11_gui, "", s:nord11_term, "", "", "")
+call s:hi("LSPDiagnosticsInformation" , s:nord8_gui, "", s:nord8_term, "", "", "")
+call s:hi("LSPDiagnosticsHint" , s:nord10_gui, "", s:nord10_term, "", "", "")
+
+
 " GitGutter
 " > airblade/vim-gitgutter
 call s:hi("GitGutterAdd", s:nord14_gui, "", s:nord14_term, "", "", "")