Documentation: updated section "Edit the Dive Info"

- Made tables of semi-formatted texts.
- Rewrote some of text because the screenshot and table are both
  about the same thing. The screenshot is more important now, the
  table is explanation of screenshot.

Signed-off-by: Reinout Hoornweg <reinout@xs4all.nl>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Documentation: update main windows image

Sent to the list by Miika for inclusion in the user manual...

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>