package level: example data pre-processing code update

There is a problem in the example data statements where days and weeks use the name number ranges so the plot example doesn't show proportional x-axis distances.

**Current example code yields**
Screening, Baseline, Week 1, Week 2, etc.
-2, 0, 1, 2, etc.

**Update should yield**
Screening, Baseline, Week 1, Week 2, etc.
-2, 0, 7, 14, etc.

Provenance:
```
Creator: npaszty
```