Add template doc for Android properties used by bluedroid.

Properties

===

This document describes all of the Android properties used by bluedroid.

Please keep the following list in alphabetical order.

### TODO (Broadcom): write descriptions of what each property means and how

it's used.

* ``` debug.sys.noschedgroups ```

* ``` persist.service.bdroid.bdaddr ```

* ``` ro.bluetooth.hfp.ver ```

* ``` ro.bt.bdaddr_path ```

* ``` ro.product.model ```

* ``` service.brcm.bt.oob ```