Please create documentation about how to deal with demo.library

[kelson42]

In a README.md

Parta of the necessary doc is already available at https://wiki.openzim.org/wiki/Content_team#Demo_a_ZIM

[benoit74]

What is missing on https://wiki.openzim.org/wiki/Content_team#Demo_a_ZIM ? (I would like to avoid having multiple places where documentation is placed, and while I agree that architecture diagrams and details would help, this is true for the whole infrastructure and we've always considered we can live without it)

[benoit74]

What is missing is an explanation of:

• what is demo library
• why we have it
• how it works (for non-technical persons)

This should be placed in this repo in a README close to demo library, so that it will live with the code (contrary to the openZIM wiki which should hold only processes and not explanations about how software works)