doc: Bluetooth: shell: Add document for Classic RFCOMM

Add a document to show how to use the Classic RFCOMM shell commands.

Signed-off-by: Lyle Zhu <[email protected]>

Author: lylezhu2012

doc/connectivity/bluetooth/bluetooth-shell.rst

@@ -25,6 +25,7 @@ For specific Bluetooth functionality see also the following shell documentation
    shell/classic/a2dp.rst
    shell/classic/hfp.rst
    shell/classic/l2cap.rst
+   shell/classic/rfcomm.rst
    shell/host/gap.rst
    shell/host/gatt.rst
    shell/host/iso.rst

doc/connectivity/bluetooth/shell/classic/rfcomm.rst

@@ -0,0 +1,108 @@
+Bluetooth: Classic: RFCOMM Shell
+################################
+
+This document describes how to run the Bluetooth Classic RFCOMM functionality.
+The :code:`rfcomm` command exposes the Bluetooth Classic RFCOMM Shell commands.
+
+Commands
+********
+
+The :code:`rfcomm` commands:
+
+.. code-block:: console
+
+   uart:~$ rfcomm
+   rfcomm - Bluetooth RFCOMM shell commands
+   Subcommands:
+     register    : [none]
+     connect     : <channel>
+     disconnect  : [none]
+     send        : <number of packets>
+     rpn         : Send RPN command with default settings
+
+Connect
+*******
+
+The ACL connection should be established before creating the RFCOMM connection.
+
+.. tabs::
+
+   .. group-tab:: Non-initializing device
+
+      .. code-block:: console
+
+         uart:~$ rfcomm  register
+         RFCOMM channel 5 registered
+         Security changed: XX:XX:XX:XX:XX:XX level 2
+         Incoming RFCOMM conn 0x20004dc8
+         Dlc 0x20000d20 connected
+
+   .. group-tab:: Initializing device
+
+      .. code-block:: console
+
+         uart:~$ rfcomm connect 5
+         RFCOMM connection pending
+         Security changed: XX:XX:XX:XX:XX:XX level 2
+         Dlc 0x20000d20 connected
+
+Send Data
+*********
+
+.. tabs::
+
+   .. group-tab:: Non-initializing device
+
+      .. code-block:: console
+
+         Incoming data dlc 0x20000d20 len 30
+         uart:~$ rfcomm send 1
+         uart:~$
+
+   .. group-tab:: Initializing device
+
+      .. code-block:: console
+
+         uart:~$ rfcomm send 1
+         Incoming data dlc 0x20000d20 len 30
+
+Disconnect
+**********
+
+Create disconnect request from non-initializing device:
+
+.. tabs::
+
+   .. group-tab:: Non-initializing device
+
+      .. code-block:: console
+
+         uart:~$ rfcomm disconnect
+         Dlc 0x20000d20 disconnected
+         uart:~$
+
+   .. group-tab:: Initializing device
+
+      .. code-block:: console
+
+         Dlc 0x20000d20 disconnected
+         uart:~$
+
+Create disconnect request from initializing device:
+
+.. tabs::
+
+   .. group-tab:: Non-initializing device
+
+      .. code-block:: console
+
+         Dlc 0x20000d20 disconnected
+         uart:~$
+
+   .. group-tab:: Initializing device
+
+      .. code-block:: console
+
+         uart:~$ rfcomm disconnect
+         Dlc 0x20000d20 disconnected
+         uart:~$