Improve parsers docstrings

[JessyBarrette]

The following parsers modules should be updated with appropriate documentation:

• [x] amundsen
• [x] electricblue
• [x] nmea
• [x] onset
• [x] pme
• [x] rbr
• [x] seabird
• [x] start_oddi
• [x] van_essen_instruments
• [x] dfo
  • [x] ios shell
  • [x] odf
  • [x] p file
• [x] automated parser detection