Docs: Add basic installation templates without Icinga Director

[LordHepipud]

We should add basic documentation for installing Icinga for Windows without the Icinga Director, by using endpoints configuration for different communication options.

[johannesst]

This would indeed be phantastic. We have several subnets without direct connection to the director. The agents communicates via a satelite with the icinga master nodes. While this works quite well with Linux and good enough for normal checks (check_disk.exe, check_load.exe etc) it leads to issues with custom checks depending on the powershell framework. My guess is, that we did something wrong during the manual setup without the self-service API.
So it would be extremely helpful to know, how to deploy IcingaForWindows without the API or alternatively how to relay the API via the satelites.

If you need a beta tester or reader I'm happy to help out.