How to configure inflow, outflow or the trusted security domains for Elytron

Book: How to Configure Identity Management
Revision: 3054cc5
Section: 4.1. Configure Web Applications to Use Elytron or Legacy Security for Authentication

Issue description:
In section 4.1. Configure Web Applications to Use Elytron or Legacy Security for Authentication in part "Using Elytron and Legacy Security Subsystems in Parallel" there is sentence "... you will need to configure the inflow, outflow or the trusted security domains so that their identity propagates from one deployment domain to the next one ...". However it seems that nowhere in documentation is described how to configure it. This information should be added.

Suggestions for improvement:
Please add information about how to technically configure inflow, outflow or the trusted security domains for two Elytron security domains - some CLI commands would be helpful. Documentation should also provide answers for following questions:

• How inflow and outflow between two security domains works
• When trusted security domains should be used
• When should be used inflow and when outflow