Create static descriptions

[zepumph]

@jessegreenberg asked me to work on implementing this document before the meeting on Thursday. I'm on it!

https://docs.google.com/document/d/1PxMAm5qjbYn_F8Buo_CH5cZ-Xb6D4ARjrAt3NAc5Kms/edit#

[zepumph]

Everything that is completely static is done, but there are still some dynamic pieces that need to be worked on. I wanted to make sure that I got the static stuff done first. Here is a list of the corners I cut:

• I changed a label, instead of updating the Alpha Particle stream to say "start" or "stop" dynamically, it just always says "toggle"
• The proton and neutron counts for the sliders are not updating.
• The playPause button is just using its default labels, instead of ours that dynamically change when toggled.

[zepumph]

@emily-phet what is the status on this? It looks like the design doc only got to the first screen, unassigning myself until it is prioritized again.