Incorrect documentation of the PLND_YAW_ALIGN parameter in MP

#### Issue details
_Please describe the problem, or desired feature_
Documentation in parameter list and parameter tree for the PLND_YAW_ALIGN parameter of AC 3.6.9 is incorrect. The unit is centidegrees, and therefore the correct value range should be 0 - 36000 and not 0 - 360.

#### Version
_What version was the issue encountered with_
MP 1.3.68

#### Platform
[ ] All
[ ] AntennaTracker
[X] Copter
[ ] Plane
[ ] Rover
[ ] Sub

#### Airframe type
_What type of airframe (flying wing, glider, hex, Y6, octa etc)_
quad

#### Hardware type
_What autopilot hardware was used? (pixhawk, pixracer, PX4FMU etc)_
Pixhawk 2.1
#### Logs
_Please provide a link to any relevant logs that show the issue_

Start with the PLND_YAW_ALIGN entries in Mission Planner's parameter list and parameter tree, using the issue's AC 3.6.9 details to verify the unit and range. Done means both documentation locations show centidegrees and a range of 0–36000 instead of 0–360.

Written by the indexing model from the issue text.