Fix default size for scrollable notebook

Linus change in commit bcb9f67819bc ("Make the notebook portion (dive
notes/equipment/info) a scrollable window") created a really ugly default where
the notebook Dive Notes always ended up with a vertical scrollbar. This picks a
much saner default layout for the panes.

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