Doc: Updated the requirements section
Doc: Updated the requirements section

Added information about the JDK by Oracle first before mentioning
the OpenJDK alternative on Linux. Also updated information about
the ADB drivers on Windows with a link that provides more details
about the download location.

Task-number: QTBUG-33580
Change-Id: Ibe6dfa2c158aa666c6a44b2b90a13400dbd4f806
Reviewed-by: Daniel Teske <d8a411aec9a206efedb4d45b75fe8d13f1e2b628@digia.com>

kobolabs/qtdoc,kobolabs/qtdoc,kobolabs/qtdoc,kobolabs/qtdoc