Improve the documentation for getting data "in NWB"

[jeromelecoq]

The pyNWB documentation is really well structured, convenient and easily usable. The API documentation is also thorough at each individual function.

Still, it is a little challenging to convert data into NWB files without getting clarifications directly from the developer community (which is very supportive and always helpful). I feel like a little more detailed step by step examples of this conversion and the underlying concepts behind it would help (When to use trials vs stimulus template, for example?)

For example, how to add stimulation information to NWB files is not entirely clear from the documentation. It will also ensure that various datasets are following good practices, since NWB still are somehow flexible into how stimulation information is stored.