User manual: Updates regarding the companion app

These adiitions and changes were made in accordance with the screenshots
provided by Venkatesh and Salvador and after managing to actually run the
companion app on my phone. Large parts of the text of this section have
been changed in accordance with the Companion V2 interface. Two graphics
were changed.

After Version 2 has stabilised, some more adaptation of the text will be
required.

Signed-off-by: Willem Ferguson <willemferguson@zoology.up.ac.za>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>