In order to use the USB port on the plug, you'll need to get a "USB On The Go" or "USB OTG" cable. Some of these have a hub built in. Here's how to enable USB hub support.
I'm typing the entries from the .config file, which I find more straightforward than referencing the menu locations in menuconfig. There's a note at the top of .config which warns you not to edit it by hand. I haven't had any issues with it so far. You'll need to run "make menuconfig" and just exit after doing this to avoid the ".config is out of sync" warning when you run "make".
Now, lsusb shows:
Bus 002 Device 002: ID 05e3:0606 Genesys Logic, Inc. USB 2.0 Hub / D-Link DUB-H4 USB 2.0 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 003: ID 0a5c:21e8 Broadcom Corp. BCM20702A0 Bluetooth 4.0
I have a Bluetooth 4.0 USB dongle plugged in, which I hope to get running with something shortly.