Update Mass Flow Rates For Aluminum Design

[Blueorchid]

Hi, at some point we need to update the mass flow rates to match the new aluminum design.

Total propellant flow rate: 2.06 lb/s
Ethanol flow rate: 0.94 lb/s
LOX flow rate: 1.13 lb/s

Not sure if it would be beneficial to combine the injector and the nozzle Jupyter notebooks into one someday, or keep them separate.

[7deeptide]

I suggest keeping the the notebooks separate. However it would be really beneficial to add notes on motivation and workflow to the git readme.

The gps board repo is an exemplar of a quality readme:
https://github.com/psas/gps-rf-board