Improve documentation on the SiriusSession option

[ylussaud]

A step by step paragraph should be added to the Capella and M2Doc documentation to set the SiriusSession option. Make sure to explain that Capella rely on Sirius in the Capella part of the documentation.

[mPorhel]

Do not hesitate to add another one (or alternative steps) to explain the corresponding steps with Team for Capella.

I see two scenarios:

• initialization of new project
• modification of a .genconf configured for a local project to work with the corresponding shared project.

[ylussaud]

Also add a step by step guide to use M2Doc with Team for Capella and OD Team.