Add a End-User Manual

[prudhomm]

The End-User should have a manual/tutorial to:

• [ ] connect on the platform
• [ ] buy an application
• [ ] provide data and access it via the data management handling
• [ ] experiment with the application
• [ ] visualize the results

Also there should be documentation for each uploaded App and we should add a button on the screen to access the specific documentation. This documentation should probably be provided in the package and available on the website (eg a README.adoc in the package that explain the different fields and connect to the underlying applications )

[prudhomm]

@victorsndvg in the end-user manual I think we should describe the general expected behavior of apps and then we have the specifics documentation for the apps in Epic #21