feat: linux: Add compilation instructions for TI Apps Launcher

meta-arago-toolchain lacks Qt6 support for compiling TI Apps Launcher.
The correct way to compile it is to use Yocto.

However, for quicker way to compile it, we can also use ARM64 Docker
containers. Provide a guide on how to compile ti-apps-launcher using
ARM64 Docker container which TI provides [0].

[0] https://github.com/TexasInstruments/ti-docker-images/pkgs/container/debian-arm64

Signed-off-by: Suhaas Joshi <s-joshi@ti.com>

Author: jsuhaas22

source/linux/Demo_User_Guides/TI_Apps_Launcher_User_Guide.rst

@@ -438,3 +438,63 @@ Power Menu
     .. Image:: /images/ti-apps-launcher-powermenu2.png
        :height: 400
 
+Compiling TI Apps Launcher
+--------------------------
+
+The ideal way to compile TI Apps Launcher is to trigger a Yocto
+build. But for a quicker way to do it, especially during development,
+TI provides a `debian-arm64
+<https://github.com/TexasInstruments/ti-docker-images/pkgs/container/debian-arm64>`__
+Docker image. This image already has all dependencies required
+for compiling ti-apps-launcher.
+
+First, clone TI Apps Launcher on host:
+
+.. code:: console
+
+   git clone https://github.com/texasinstruments/ti-apps-launcher.git
+   export TI_APPS_LAUNCHER_REPO="$(pwd)/ti-apps-launcher"
+   cd ti-apps-launcher
+
+Then, add the following line in :file:`CMakeLists.txt`:
+
+.. code:: console
+
+   add_compile_definitions(SOC_AM62=1) # if target is AM62x or AM62SIP
+   add_compile_definitions(SOC_AM62_LP=1) # if target is AM62x-LP
+   add_compile_definitions(SOC_AM62P=1) # if target is AM62P
+
+Then, pull TI's debian-arm64 Docker image and run it:
+
+.. code:: console
+
+   docker pull ghcr.io/texasinstruments/debian-arm64:latest
+   docker run -it -v ${TI_APPS_LAUNCHER_REPO}:/root/ti-apps-launcher ghcr.io/texasinstruments/debian-arm64 bash
+
+Finally, run:
+
+.. code:: console
+
+   cmake -B build -S . -DRT_BUILD=0 # if target is RT image, make -DRT_BUILD=1
+   make -C build
+
+The compiled binary should be :file:`build/ti-apps-launcher`.
+
+Copy the compiled binary to :file:`/usr/bin/` directory of the target:
+
+.. code:: console
+
+   scp ${TI_APPS_LAUNCHER_REPO}/build/ti-apps-launcher root@<ip-addr-of-device>:/usr/bin
+
+If you have modified the scripts in the :file:`scripts/` directory, then copy them too:
+
+.. code:: console
+
+   scp -r ${TI_APPS_LAUNCHER_REPO}/scripts root@<ip-addr-of-device>:/opt/ti-apps-launcher
+
+.. note::
+
+   This is a quick and easy way to compile ti-apps-launcher during
+   development, but it is a good idea to validate with Yocto builds
+   often. There is a possibility that compiler mismatch could present
+   issues in the run up to production.