I am 100% behind you on this one. Some simple diagrams showing how individual nodes and GrayLog talk to each other would be nice. As well as some ‘sample’ conf files with all the fields filled in as per the sample diagram would help.
I know writing manuals and instructions sucks, have hated that part of my job for the entire 40 years doing this. That being said, have learned some tricks. The best one, for something like GreyLog, is give the setup instructions to someone who knows computers, but does not know GreyLog. Let them attempt a simple install following your instructions. If they can’t get it to work, the instructions need work. This can be done by the person creating the system, but almost always the person writing the system will use knowledge not explicitly put into the instructions.
Putting my money where my mouth is, if you would like, I will volunteer the test of the ‘guinea pig’ tester.