Containers : create a documentation

[MaiaDereva]

Write a documentation to help user with understanding containers and how to use it (document by example by taking existing projects)

[balessan]

A base of the documentation can be found in the wiki: https://github.com/assemblee-virtuelle/wpldp/wiki

But it is only really basic stuff and setup. Need to improve it, and move somewhere else to get it in different languages.