Merge pull request #496 from igillespie/typos-in-documentation

Improvements to extra parts documentation

parts_list/extra_parts.md

@@ -73,10 +73,9 @@ You will want threadlocker for several screws so that they don't unscrew themsel
 * Voltage Regulators:
   * **1 X** 5V Regulator: [Pololu](https://www.pololu.com/product/2881)
   * **1 X** 12V Regulator: [Pololu](https://www.pololu.com/product/2855)
-* **1 X** PCA9685 corner: [Mouser](https://www.mouser.com/ProductDetail/Adafruit/815?qs=GURawfaeGuCGKbWyy9179Q%3D%3D)
 * **3 X** Roboclaw 2x7A Motor Controller [Basic Micro](https://www.basicmicro.com/Roboclaw-2x7A-Motor-Controller_p_55.html)
 * **1 X** Power Measurement Unit INA260: Sold out on DigiKey, possible replacements are on [Adafruit](https://www.adafruit.com/product/4226?gclid=CjwKCAjw5dqgBhBNEiwA7PryaLOm_zC9GhlzRH1NwN4bSRwDg84sIhSh3LEqTOrIvQ3j_kRBscTAYhoCBOQQAvD_BwE)
-* **1 X** PCA9685 corner motor driver [Mouser](https://www.mouser.com/ProductDetail/Adafruit/815?qs=GURawfaeGuCGKbWyy9179Q%3D%3D)
+* **1 X** PCA9685 steering servo driver [Mouser](https://www.mouser.com/ProductDetail/Adafruit/815?qs=GURawfaeGuCGKbWyy9179Q%3D%3D)
 * DC power meter: [Amazon](https://www.amazon.com/gp/product/B017FSED9I/). This LCD display reads out current, voltage, power, and energy, and can be put on the back where the rectangular hole is in the laser cut cover.
 * batteries: many options available here. We recommend getting LiPo batteries. You'll need a battery that can provide over 14V(*), so a 4s battery works well. You can get batteries with various mAh ratings (how many milliAmperes the battery can output for 1 hour). We recommend any option over 4000mAh. Higher capacity comes at a higher cost. You can also get more than one battery and swap them out. The rover can carry them as well.
   * Zeee sells many options [on Amazon](https://www.amazon.com/stores/page/25B7018D-26CC-4E43-BC6D-EFAF737D8F5E?ingress=2&visitId=1b4115fa-2240-424d-a0e6-a466830819ce&ref_=ast_bln)