DynamicsDimension description fixes

The description for the dimension 'rate' says that it's constant, which would imply that choosing the dimension 'rate' automatically defines the shape as linear. But for the 'sinusoidal' shape the rate can also be reasonably defined as the maximum rate. For 'cubic' I'm not sure if it can be defined in a reasonable way. Therefore the rate description should be changed to:
A predefined rate (constant rate for linear shape and maximum rate for sinusoidal shape) is used to acquire the target value. Not to be used for shapes 'step' and 'cubic'.