New examples for astakos, sketch up to projects
Refs: #4752
Complete updating documentation
Refs: #4692
Update docs up to examples/imageregister
Update examples for config
Fix image register example sin documentation
Problem: it was not clear if properties are mandatory in image registration
Make delete cluster docs a bit more intuitive
Refs: #4429
Add some documentation for cluster management
Update and correct kamaki.clients documentation
Take care of the documentation (except developers)
Make numerous minor fixes in documentation