programs/editors/neovim: add back indent for nix files

modules/programs/editors/neovim.nix

@@ -27,6 +27,15 @@
             vim.opt.formatoptions:remove('c')
             vim.opt.formatoptions:remove('r')
             vim.opt.formatoptions:remove('o')
+
+            vim.api.nvim_create_autocmd("FileType", {
+              pattern = "nix",
+              callback = function(opts)
+                local bo = vim.bo[opts.buf]
+                bo.tabstop = 2
+                bo.shiftwidth = 2
+              end
+             })
           '';
 
           maps = {