The Android SDK installation experience has changed since
the latest release of SDK tools package. So the getting
started info. is restructured to accommodate this change.

Change-Id: I96d463e5e1584d8054feffca97ae9cf61695530a
Task-number: QTBUG-58591
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Vikas Pachdha <vikas.pachdha@qt.io>
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>