doc/develop/manifest/external: add Zephelin

Add Zephelin [1], a Zephyr Profiling Library as an external module of the
Zephyr Project.

1: https://github.com/antmicro/zephelin

Signed-off-by: Filip Kokosinski <[email protected]>

Author: fkokosinski

doc/develop/manifest/external/zephelin.rst

@@ -0,0 +1,79 @@
+.. _external_module_zephelin:
+
+Zephelin
+########
+
+Introduction
+************
+
+`Zephyr Profiling Library`_ (ZPL), or Zephelin for short, is a library which enables capturing
+and reporting runtime performance metrics for profiling and detailed analysis of Zephyr
+applications, with a special focus on applications running AI/ML inference workloads.
+
+In addition to the above, Zephelin also simplifies the analysis of AI runtimes, such as `LiteRT`_
+and `microTVM`_, allowing you to gain a better understanding of the underlying bottlenecks or
+potential opportunities for optimization.
+
+Zephelin features:
+
+* Tracing execution of Zephyr applications on hardware
+* Obtaining traces using such backends as UART, USB or debug adapter
+* Delivering traces in CTF and TEF formats
+* Scripts for capturing traces from device
+* Collecting readings from:
+
+  * Memory - stack, heaps, kernel heaps and memory slabs
+  * Sensors - e.g. die temperature sensors
+  * Thread analysis - CPU usage
+  * AI runtimes - e.g. tensor arena usage in LiteRT
+
+* Displaying details on executed neural network layers in the LiteRT or microTVM runtime:
+
+  * Dimensions of inputs, outputs and weights
+  * Parameters of layers
+  * Time and resources spent on executing specific layers
+
+* Compilation-level and runtime-level configuration of the library
+
+* Ability to configure a profiling tier, controlling the subsystems and the amount of data collected
+
+All of the above can be analyzed with `Zephelin Trace Viewer`_.
+
+Usage With Zephyr
+*****************
+
+To use Zephelin as a Zephyr :ref:`module <modules>`, add the following entry:
+
+.. code-block:: yaml
+
+   manifest:
+     projects:
+       - name: zephelin
+         url: https://github.com/antmicro/zephelin
+         revision: main
+         path: modules/zephelin # adjust the path as needed
+
+to a Zephyr submanifest (e.g. ``zephyr/submanifests/zephelin.yaml``) and run ``west update``, or
+add it as a West project in your project's ``west.yaml`` manifest.
+
+Please consult the `Zephelin documentation`_ for more information.
+
+References
+**********
+
+.. target-notes::
+
+.. _Zephyr Profiling Library:
+   https://github.com/antmicro/zephelin
+
+.. _Zephelin documentation:
+   https://antmicro.github.io/zephelin/
+
+.. _Zephelin Trace Viewer:
+   https://antmicro.github.io/zephelin-trace-viewer
+
+.. _LiteRT:
+   https://ai.google.dev/edge/litert
+
+.. _microTVM:
+   https://tvm.apache.org/docs/v0.9.0/topic/microtvm/index.html