doc: Modernize steps to be followed after release

Remove old references to sourceforge, add what actually should be done
and provide some more details.
build: Fix windows configure when using --with-qt-libdir

fixes #4630

Github-Pull: #4633
Merge pull request #4626

e1eb741 doc: Modernize steps to be followed after release (Wladimir J. van der Laan)
[Qt] re-work overviewpage UI

- ensure normal and watch-only stuff looks consistent
- simplify UI by removing unneeded UI layout elements
- always show watch-only elements