My first pass in updating use-case documentation

[silviamazzoni]

I have made significant updates to the seismic use cases.
I have also updated the wind cases.

[wesleyboar]

I've got one link syntax fix (I'll commit it), and a question.

[silviamazzoni]

not sure why i had to review this..

[silviamazzoni]

@wesleyboar you can see here that I had to add

OpenSees Model Calibration

plus, the single # in the first line of the original file, which was his title, messed up the hierarchy

[wesleyboar]

Hm, okay. I am familiar with that problem (from TACC-Docs). Thanks for the reminder.

After my work, I'll be comfortable showing you how we can include documents with lower or higher level heading hierarchies, yet still render in nav appropriately.

[silviamazzoni]

Are we now just waiting for @susanunit to approve?

[susanunit]

Apologies for the delay. Approved.

[silviamazzoni]

Thank you, Susan for the approval.
Now someone needs to merge this...