Create README.md for Matter Linux Contact Sensor Example (#33563)

* Create README.md for Matter Linux Contact Sensor Example

* Update README.md

* Update README.md

[PATCH] Restyled by prettier-markdown

* Update README.md

Fix 'RPC Console' section

* Update examples/contact-sensor-app/linux/README.md

Co-authored-by: Kiel Oleson <kielo@apple.com>

* Update examples/contact-sensor-app/linux/README.md

Co-authored-by: Kiel Oleson <kielo@apple.com>

* Update examples/contact-sensor-app/linux/README.md

Co-authored-by: Kiel Oleson <kielo@apple.com>

* Restyled by prettier-markdown

---------

Co-authored-by: Kiel Oleson <kielo@apple.com>

Author: lboue

examples/contact-sensor-app/linux/README.md

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+# Matter Linux Contact Sensor Example
+
+An example showing the use of CHIP on the Linux. This document will describe how
+to build and run Matter Linux Contact Sensor Example on Raspberry Pi. This
+document is tested on **Ubuntu for Raspberry Pi Server 20.04 LTS (aarch64)** and
+**Ubuntu for Raspberry Pi Desktop 20.10 (aarch64)**
+
+To cross-compile this example on an x64 host and run it on **NXP i.MX 8M Mini**
+**EVK**, see the associated
+[README document](../../../docs/guides/nxp/nxp_imx8m_linux_examples.md) for
+details.
+
+<hr>
+
+-   [Matter Linux Contact Sensor Example](#matter-linux-contact-sensor-example)
+    -   [Building](#building)
+    -   [Commandline Arguments](#commandline-arguments)
+    -   [Running the Complete Example on Raspberry Pi 4](#running-the-complete-example-on-raspberry-pi-4)
+    -   [Running RPC console](#running-rpc-console)
+    -   [Device Tracing](#device-tracing)
+
+<hr>
+
+## Building
+
+-   Install tool chain
+
+          $ sudo apt-get install git gcc g++ python pkg-config libssl-dev libdbus-1-dev libglib2.0-dev ninja-build python3-venv python3-dev unzip
+
+-   Build the example application:
+
+          $ cd ~/connectedhomeip/examples/contact-sensor-app/linux
+          $ git submodule update --init
+          $ source third_party/connectedhomeip/scripts/activate.sh
+          $ gn gen out/debug
+          $ ninja -C out/debug
+
+-   To delete generated executable, libraries and object files use:
+
+          $ cd ~/connectedhomeip/examples/contact-sensor-app/linux
+          $ rm -rf out/
+
+-   Build the example with pigweed RPC
+
+          $ cd ~/connectedhomeip/examples/contact-sensor-app/linux
+          $ git submodule update --init
+          $ source third_party/connectedhomeip/scripts/activate.sh
+          $ gn gen out/debug --args='import("//with_pw_rpc.gni")'
+          $ ninja -C out/debug
+
+## Commandline arguments
+
+-   `--wifi`
+
+    Enables WiFi management feature. Required for WiFi commissioning.
+
+-   `--thread`
+
+    Enables Thread management feature, requires ot-br-posix dbus daemon running.
+    Required for Thread commissioning.
+
+-   `--ble-device <interface id>`
+
+    Use specific bluetooth interface for BLE advertisement and connections.
+
+    `interface id`: the number after `hci` when listing BLE interfaces by
+    `hciconfig` command, for example, `--ble-device 1` means using `hci1`
+    interface. Default: `0`.
+
+## Running the Complete Example on Raspberry Pi 4
+
+> If you want to test Echo protocol, please enable Echo handler
+>
+>     gn gen out/debug --args='chip_app_use_echo=true'
+>     ninja -C out/debug
+
+-   Prerequisites
+
+    1. A Raspberry Pi 4 board
+    2. A USB Bluetooth Dongle, Ubuntu desktop will send Bluetooth advertisement,
+       which will block CHIP from connecting via BLE. On Ubuntu server, you need
+       to install `pi-bluetooth` via APT.
+    3. Ubuntu 20.04 or newer image for ARM64 platform.
+
+-   Building
+
+    Follow [Building](#building) section of this document.
+
+-   Running
+
+    -   [Optional] Plug USB Bluetooth dongle
+
+        -   Plug USB Bluetooth dongle and find its bluetooth device number. The
+            number after `hci` is the bluetooth device number, `1` in this
+            example.
+
+                  $ hciconfig
+                  hci1:	Type: Primary  Bus: USB
+                      BD Address: 00:1A:7D:AA:BB:CC  ACL MTU: 310:10  SCO MTU: 64:8
+                      UP RUNNING PSCAN ISCAN
+                      RX bytes:20942 acl:1023 sco:0 events:1140 errors:0
+                      TX bytes:16559 acl:1011 sco:0 commands:121 errors:0
+
+                  hci0:	Type: Primary  Bus: UART
+                      BD Address: B8:27:EB:AA:BB:CC  ACL MTU: 1021:8  SCO MTU: 64:1
+                      UP RUNNING PSCAN ISCAN
+                      RX bytes:8609495 acl:14 sco:0 events:217484 errors:0
+                      TX bytes:92185 acl:20 sco:0 commands:5259 errors:0
+
+        -   Run Linux Contact Sensor App
+
+                  $ cd ~/connectedhomeip/examples/contact-sensor-app/linux
+                  $ sudo out/debug/chip-contact-sensor-app --ble-device [bluetooth device number]
+                  # In this example, the device we want to use is hci1
+                  $ sudo out/debug/chip-contact-sensor-app --ble-device 1
+
+        -   Test the device using ChipDeviceController on your laptop /
+            workstation etc.
+
+## Running RPC Console
+
+-   As part of building the example with RPCs enabled the chip_rpc python
+    interactive console is installed into your venv. The python wheel files are
+    also created in the output folder: out/debug/chip_rpc_console_wheels. To
+    install the wheel files without rebuilding:
+    `pip3 install out/debug/chip_rpc_console_wheels/*.whl`
+
+-   To use the chip-rpc console after it has been installed run:
+    `chip-console -s localhost:33000 -o /<YourFolder>/pw_log.out`
+
+-   Then you can Get the contact sensor status using the RPCs:
+    `rpcs.chip.rpc.BooleanState.Get()`
+
+## Device Tracing
+
+Device tracing is available to analyze the device performance. To turn on
+tracing, build with RPC enabled. See [Building with RPC enabled](#building).
+
+To obtain the tracing json file, run:
+
+```
+    $ ./{PIGWEED_REPO}/pw_trace_tokenized/py/pw_trace_tokenized/get_trace.py -s localhost:33000 \
+     -o {OUTPUT_FILE} -t {ELF_FILE} {PIGWEED_REPO}/pw_trace_tokenized/pw_trace_protos/trace_rpc.proto
+```