Adding the other principle sections - software design

[RobJohnsonHO]

Discussed in #23

^{Originally posted by RobJohnson-HO April 11, 2022}
Trying out the announcement feature discussion.

I will start a new feature branch for the software design top level principles. I'll try creating issues off this discussion and see how the flow works.

We can drop updates in discussion and any problems/issues etc...