f_q.md: A few notes

[sagehane]

1. SKWARB (squash) mentioned in https://www.artofchording.com/sounds/f_q.html#left-side-q uses -RB, which is covered in a later section (https://www.artofchording.com/sounds/sh.html). I couldn't tell if this was intentional but it did confuse me as a beginner.
   • The 8th exercise in https://www.artofchording.com/sounds/f_q.html#_1-translate also mentions SKWARBD.
2. The 1st exercise translates to "If you help me out I will help you back.", and I think a comma might be appreciated in the middle.

Edit: The first issue I addressed is just a duplicate of #85, sorry.