Clarify how "inf" and "nan" shall be used with units
Based on the discussion of https://code.asam.net/simulation/openscenario/2.x/-/merge_requests/484 there are two possible solutions here
- one option is to separate them with space, i.e.
inf kph - Another option is to put the units inside bars, i.e.
inf|kph|
An example and explicit explanation in the manual of this shall be prepared.