Improve HIG for Calc Data Statistics .ui, ANOVA

Change-Id: I3e51685cf4049615e3fc4c562f52a23797c3f4c1
Reviewed-on: https://gerrit.libreoffice.org/10684
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
Tested-by: Tomaž Vajngerl <quikee@gmail.com>