Documentation fixes. (#1811)

Update documentation text and links.
Fix spelling errors.
Other minor adjustments where appropriate, such as remove whitespaces and format code.

Moose Development/Moose/Wrapper/Positionable.lua

@@ -725,7 +725,7 @@ function POSITIONABLE:InAir()
   return nil
 end
 
---- Returns the a @{Velocity} object from the POSITIONABLE.
+--- Returns the @{Core.Velocity} object from the POSITIONABLE.
 -- @param #POSITIONABLE self
 -- @return Core.Velocity#VELOCITY Velocity The Velocity object.
 -- @return #nil The POSITIONABLE is not existing or alive.