nixpkgs/neovim: use nil language server if present

.config/nixpkgs/neovim/lsp.lua

@@ -87,6 +87,12 @@ if vim.fn.executable("solargraph") == 1 then
   })
 end
 
+if vim.fn.executable("nil") == 1 then
+  nvim_lsp.nil_ls.setup({
+    on_attach = on_attach,
+  });
+end
+
 local group = vim.api.nvim_create_augroup('LspFormatting', { clear = false })
 
 null_ls.setup({