Zephyr: External module documentation

[rascani]

Submit documentation to the Zephyr external projects/modules registry describing how to integrate ExecuTorch with a Zephyr project. Validate the integration on a single board and provide at least one basic inference sample.

Upstream module acceptance is not on the table (see zephyrproject-rtos/zephyr#92981), so the goal is a well-documented external module path.

• ExecuTorch listed as an external module in Zephyr documentation
• Integration tested on at least one board (e.g., Nordic nRF, STM32, Alif E8)
• At least 1 basic inference sample compiles and runs via west build
• README or doc page with step-by-step integration instructions

cc @digantdesai @SS-JIA @freddan80 @per @zingo @oscarandersson8218 @mansnils @Sebastian-Larsson @robell @psiddh @AdrianLundell

[itsMarco-G]

Hello @rascani I have spoken to our executorch team (including @zingo) and I will be picking up this work, it is also going to be my priority in the next few days

[rascani]

Sounds good. Please coordinate with @psiddh, as he also expressed interest in working on this.

[itsMarco-G]

Great, @psiddh I can tag you on a fork/branch i'll make from the Zephyr repo for this work, and you're welcome to contribute and ideas welcome!

[itsMarco-G]

Hello @psiddh i invited you to collaborate in my zephyr fork, where I have the branch and commit for this work. It is very close to being complete, I just need to test on windows and ubuntu machines. It would be great to get your feedback on it.

There is also a way to generate the docs locally which i have done throughout to test it: https://docs.zephyrproject.org/latest/contribute/documentation/generation.html

i suggest doing that if you would like to go through it

[itsMarco-G]

[Edit] Update: Turns out below isn't required for external modules

Created this: zephyrproject-rtos/zephyr#105049

as per: https://docs.zephyrproject.org/latest/contribute/external.html#external-contributions

[itsMarco-G]

Hello all, just going through some initial internal reviews but here is my branch with the docs update: zephyrproject-rtos/zephyr@main...itsMarco-G:zephyr:doc/executorch-external-module