Creating the Zone Artcle

When i created the article it was just a copy from the catala wiki. Maybe it is better to move the article to "Creating a zone".

Description of a zone needs in my opinion references to

• the hierarchical structure of zones in Guifi.net
• the consisting nodes
• tasks to be fulfilled by the zone maintainers
• how to get a maintainer
• examples

But not necessarrily tiny details like defaut proxy.