Elastic Docker example should only contain Elastic examples

[KilimAnnejaro]

From #8:

Description
In the elastic docker example, pygeoapi is configured to serve 4 datasets, but only 1 of them is actually using elastic as a backend provider.

Steps to Reproduce
Start the docker-compose file and navigate to the collections page. You will see 4 datasets there.

These datasets use different providers: CSV, GeoJSON, SQLiteGPKG. Only one of them uses elastic.

Expected behavior

In this example, we should publish only the dataset that is served using the elastic provider:

In order to achieve this, you can edit the pygeoapi configuration file to remove all the datasets that are not published using the elastic provider.

[tomkralidis]

Closing in lieu of #8 (now transferred here).