Examples of NIDM Experiment 

I've added examples of the NIDM Experiment object model:

- Project level: high level project details, similar to that in the dataset descriptor level
- Study level: a collection of acquisitions from the same time period (e.g., fmri + pulse/oxygen or a neuropsych battery)
- Acquisition level: a single stream of data observation (e.g., fmri timeseries, mmse, n-back, etc.)