Added more help info in preferences

[shun2wang]

Added more and improved help files in preferences helpfile

• [x] missing value labels, part of jasp-issues#1708
• [x] Windows workaround
• [x] normalized notation ->exponent notation
• [x] Use Qt's textrendering

to be added:

• [ ] maximum engine count INTERNAL-jasp#2121 (comment)
• [ ] Netherlands languages in _nl.md

anybody could review and add more info directly against this PR?