The pre-built Docker image lacks an input to change the baseURL

[mvanbrab]

The new -b option to comunica-web-client-generator or ./bin/generate.js hardcodes the baseURL in the packaged code.

As a result, a next version of the pre-built image would only work for https://query.linkeddatafragments.org/.

We need an instruction to modify the baseURL at container creation time.

Or some other solution to avoid that all projects need to start from sources...