Enhance Documentation

* Add example on how to deploy Mesh UI within custom path on a frontend server
* To make sure that the example Elasticsearch/GraphQL queries in the documententation are working, we should create automatic tests for these queries against the demo project.

Start by locating the documentation, demo project, and existing Elasticsearch/GraphQL query examples; no specific files or test entry points are named. Done means documenting deployment of Mesh UI under a custom frontend-server path and adding automatic checks that the example queries work against the demo project.

Written by the indexing model from the issue text.