Add nvim-lazy submodule and add plugin configuration.

pkgsets/nvim/lsp/ltex.nix

@@ -0,0 +1,24 @@
+{
+  lib,
+  config,
+  pkgs,
+  ...
+}:
+
+lib.optionalString (lib.elem "nvim::lsp::ltex" config.machine.pkgs) # lua
+  ''
+      lspconfig.ltex.setup({
+        cmd = { "${pkgs.ltex-ls}/bin/ltex-ls" },
+        settings = {
+          ltex = {
+    		  	language = "de-DE",
+    		  },
+        },
+      })
+
+      vim.api.nvim_create_user_command(
+        "LtexLang",
+        "lua SetLtexLang(<q-args>)",
+        { nargs = 1, desc = "Set ltex-ls language" }
+      )
+  ''