Heavily reworked with advice from Alan Agius.
FWIW
* `ng test` fails because there are no unit tests
* `yarn e2e` builds but fails - `Unable to start a WebDriver session.`
**Added `readme.md` to sample code**
Makes it easier for the casual downloader to try the example.
**Added `universal-ngmodule`**
The existing ngModule-based doc has a lot of guidance for developers who are still building with NgModule. Given that we are preserving the existing NgModule guidance (with modifications), it seems prudent to preserve the NgModule form of the Universal guidance. So I copied the existing guide and code to `universal-ngmodule` and added it to the left-side navigation under the "NgModules" sub-tree.
Warning: it retains all of the faults of the original guide ... faults that were addressed in the current revision.
PR Close#51564
Ward Bell