Adapt web browser example to new web site.

- Change URL to qt.io.
- Save version number to settings and overwrite saved bookmarks
  unless version exists (enabling further updates depending on version).
- Save geometry and make initial geometry large to accommodate qt.io
  and High DPI screens.

Task-number: QTBUG-41798
Task-number: QTBUG-38858
Change-Id: I4da1d6e66135ff2867b6c678f5742767dbcb59fd
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Doc: Applied title case to section1 titles

Task-number: QTBASE-41250
Change-Id: I1c766c3be413d1ed010665522c4e559d16a4f3a6
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>
Merge remote-tracking branch 'origin/5.4' into dev

Change-Id: I1961b2fa015b4fc50b13379d357cb9be4af21631
Merge "Merge remote-tracking branch 'origin/5.4' into dev" into refs/staging/dev