Model.md

+The `model` module reads the data in [shake_data.hdf](http://usgs.github.io/shakemap/manual4_0/tg_formats.html#shake-data-hdf) and produces an interpolated ShakeMap, and adds [shake_result.hdf](http://usgs.github.io/shakemap/manual4_0/tg_formats.html#shake-result-hdf) to the `current/products` directory. Note that the outputs are placed in the `[shakemap]/tests/data/eventdata/northridge/current/products` directory. The `current` subdirectory is to manage multiple versions of shakemap for this event. 
+```
+> shake northridge model
+INFO ; 2018-02-09 14:12:52 ; shake.main ; Running command model
+INFO ; 2018-02-09 14:13:49 ; shake.main ; Finished running command model: Elapsed 57.12 secs
+```