Create sim primer

[arouinfar]

Tracking sim primer publication in this issue, so that #1 can be closed.

[arouinfar]

Marking as on-hold until the following primers are published:

• [x] https://github.com/phetsims/circuit-construction-kit-dc/issues/167
• [x] https://github.com/phetsims/circuit-construction-kit-dc-virtual-lab/issues/10
• [x] https://github.com/phetsims/projectile-motion/issues/147
• [x] https://github.com/phetsims/pendulum-lab/issues/191
• [ ] https://github.com/phetsims/capacitor-lab-basics/issues/235

[arouinfar]

Since CLB has some pending changes, this sim is up next.

• [x] Draft script - 5/1/18
• [x] Record rough version for script verification - 5/31/18
• [x] Review script verification draft, and adjust script as necessary - 6/1/18
• [x] Record another draft - 6/5/18
• [x] Review 2nd draft - 6/5/18
• [x] Produce primer and upload 6/6/18
• [x] Caption primer 6/6/18

[arouinfar]

The primer is now live, thanks @CWilson4960!