doc: build: sysbuild: Clarify TF-M build targets

Not all build targets for images are given equivalent prefixed build targets

when sysbuild is used, for example build targets like ``ram_report``,

``rom_report``, ``footprint``, ``puncover`` and ``pahole`` are not exposed.

When using :ref:`Trusted Firmware <tfm_build_system>`, this includes build

targets prefix with ``tfm_`` and ``bl2_``, for example: ``tfm_rom_report``

When using :ref:`Trusted Firmware <tfm_build_system>`, the build targets prefixed

with ``tfm_`` and ``bl2_`` are also not exposed, for example: ``tfm_rom_report``

and ``bl2_ram_report``. To run these build targets, the build directory of the

image can be provided to west/ninja/make along with the name of the build

target to execute and it will run.

         west build -d build/mcuboot -t rom_report

      For TF-M projects using TF-M targets, the application build directory is

      used like so:

      .. code-block:: shell

         west build -d build/<app_name> -t tfm_rom_report

   .. group-tab:: ``ninja``

      Assuming that a project has been configured using ``cmake`` and built

         ninja -C mcuboot rom_report

      For TF-M projects using TF-M targets, the application build directory is

      used like so:

      .. code-block:: shell

         ninja -C <app_name> -t tfm_rom_report

   .. group-tab:: ``make``

      Assuming that a project has been configured using ``cmake`` and built

         make -C mcuboot rom_report

      For TF-M projects using TF-M targets, the application build directory is

      used like so:

      .. code-block:: shell

         make -C <app_name> -t tfm_rom_report

.. _sysbuild_zephyr_application:

Adding Zephyr applications to sysbuild