modules/lsp/servers: Fix lua_ls example

Example was referring to `luals` instead of `lua_ls`

(cherry picked from commit 1c5c991)

Author: shazow

modules/lsp/servers/default.nix

@@ -103,7 +103,7 @@ in
             multilineTokenSupport = true;
           };
         };
-        luals.enable = true;
+        lua_ls.enable = true;
         clangd = {
           enable = true;
           settings = {