Doc: Added information about required QML library directories.

-mentioned QT_INSTALL_QML in deployment article.
-pointed to existing documentation and Qt Creator manual.
-WS and section fixes to accommodate new section.

Task-number: QTBUG-33296
Change-Id: Ic18d65a2323b4e5a8dd01a6f4f4fe436c7555c75
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>