Add an overview page for Developing Qt for Python applications.
It contains links to Python-related information in the manual
and some sections about setting up the development environment.
Task-number: QTCREATORBUG-28996
Change-Id: If5a442415bad65aa94aa78183d44c6e0f78e317e
Reviewed-by: Shyamnath Premnadh <Shyamnath.Premnadh@qt.io>
