Doc: Fixed broken links and other style issues.

-primarily fixed broken links, but fixed surrounding content.

Task-number: QTBUG-33360
Change-Id: Ic38e8e13d84beb0c0ed883041387216eacd1291f
Reviewed-by: Sze Howe Koh <szehowe.koh@gmail.com>
Reviewed-by: Venugopal Shivashankar <venugopal.shivashankar@digia.com>
Reviewed-by: Geir Vattekar <geir.vattekar@digia.com>