Creating section on customizing the ANMS

[d-linko]

Include a new section in documentation on different ways to customize the ANMS
including

• what default ADMS are included
• what default agents are used

[BrianSipos]

Please keep in mind the distinction of what is a "user" of ANMS, which per the architecture is always on the other side of the HTTP gateway. Users cannot manipulate containers or their configurations, but maintainers or developers can do that.