Writing a Documentary Treatment

What are the 3 key things that this article tells the viewer to keep in mind?  Why are they important? 

The main thing I learned was that there's no template to making a documentary treatment. It can be "a script (not unlike a fictional narrative script), a story outline, a treatment, a creative brief or an audio-visual breakdown." It's also important to keep in mind that while writing a script, you want to try to keep viewers on their toes while watching the documentary. You should keep them asking for more and keep them curious. Writing a synopsis might also be valuable, and help you keep all your shots on the right track to use to use.