samples: hci_uart: Add references to sections

Add a couple of references so that we can link to those from other
documentation sections.

Signed-off-by: Carles Cufi <[email protected]>

Author: carlescufi

samples/bluetooth/hci_uart/README.rst

@@ -53,6 +53,8 @@ For example, to build for the nRF52832 Development Kit:
    :board: nrf52_pca10040
    :goals: build flash
 
+.. _bluetooth-hci-uart-qemu:
+
 Using the controller with QEMU
 ==============================
 
@@ -80,6 +82,8 @@ Linux kernel identifies the attached controller.
 Once the controller is attached follow the instructions in the
 :ref:`bluetooth_qemu` section to use QEMU with it.
 
+.. _bluetooth-hci-uart-bluez:
+
 Using the controller with BlueZ
 ===============================