[Docs] Example config.json for `lb4 <command>` except `lb4 app` shows the app-config.json

## Description / Steps to reproduce / Feature proposal
In the CLI generator docs e.g. https://loopback.io/doc/en/lb4/Model-generator.html, the example `--config` option shows the `lb4 app` example. This is true for Application, Datasource, Repository, etc. generators (7 generators in total).

## Expected Behavior
We should show the appropriate config json file that the commands are expecting. Find a dynamic way to update https://github.com/strongloop/loopback-next/blob/master/docs/site/includes/CLI-std-options.md for each command.

Start with docs/site/includes/CLI-std-options.md and compare its --config example with the CLI generator documentation, including the seven generators named in the issue. Determine how each command’s expected config JSON is represented, then update the documentation so every command shows the appropriate example and verify the affected generator pages.

Written by the indexing model from the issue text.