Specify units for distance and frequency

[Zacho2]

Is your feature request related to a problem? Please describe.
I downloaded the iOS client and wasn't sure if the frequency was seconds or minutes. The default of 300 made me think seconds. The distance is empty, so I had no idea. I realize there's documentation (https://www.traccar.org/blog/traccar-client-4-2/), but the client could have saved me the googling.

Describe the solution you'd like
Add units in parenthesis next to the client setting name (e.g. Distance (m))

Describe alternatives you've considered
N/A

Additional context
N/A