I can't suggest to you how to write a manual in details, even if i noticed many people is doing it in a really professional way. I don't have the technical competences and i also guess you already have your idea of how to write it in general and what structure it should have.
If i'm not wrong, you were looking for new ideas that could give to the training manual something special and different, so, here's mine:
Personally i'd find really really useful and fun to try, some short but really precise chapters dedicated to the "How to".
How to obtain specific results or to be able to film certain subject in particoular day time/situations, covering both software/technical explanations and pro-pilot tips 360º.
For example (i'm not a pro pilot, so these are just a silly examples to explain my idea don't laugh too loud
)
"How to obtain a fluid 'National Geographic' style flyby video".Level of difficulty easy-medium.
-Video setting suggestion:
-for ex 60fps-, etc
-Detailed camera setting (depending of the time of the day etc)
-Reactivity settings of the control sticks
-Director tips: (where subject should be in the video, centered on a side etcetc)
Or
How to shoot a picture/video of yourself on top of a mountain "pro/climber style" - Level of difficulty: Medium
-Suggestions for drone settings
-Procedures for using P mode, for using features like POI in this case
-Warning on possible dangers of flying near cliffs(winds, etc)
-Possible and normal pilot emotions that could come out in these particoular situations and how to react to them etc.
Or
"How to take a good night shot":
-Camera settings (Ev, contrast etcetc)
-Fears of flying by night (i can't see my drone well, so tips like using correctly map and screen infos to feel safer)
-Aternatives and possible causes in case the shot doesnt come out as expected etc
(Not balances props creating vibrations etc).
You can add lots of typical classic shots or famous movie scenes to the "How to" section and give all hints and tips to get similar results.
The "How to section" could include short sample videos or sample pics giving a fast idea of what you could achieve following those istructions, making it easy and fun to learn, giving great satisfactions.
Newbies or even advanced users could find this extremly helpful and fun and could add variation themself using it as a starting point.
I know my english is not that perfect and i know my examples are really stupid and generic but i hope i've been able to let you understand my idea.
Thanks!
Tommaso