Docs/build: clarify how to obtain ./tools/pmunts_muntsos/config-pin.c referenced by Makefile/docs

[immortal71]

Summary

The Makefile and some documentation reference building config-pin from ./tools/pmunts_muntsos/config-pin.c (e.g., gcc -o config-pin ./tools/pmunts_muntsos/config-pin.c), but config-pin.c is not included in the repository by default. The repo provides tools/pmunts_muntsos/grab_latest.sh which fetches config-pin.c from upstream, but this fetch step is not mentioned in the Makefile or in the docs that show the gcc command.

Why this is an issue

• Users following the docs (e.g., books/beaglebone-cookbook/06iot/iot.rst) might run the gcc command and fail because config-pin.c is absent.
• A short note or minor automation would remove confusion and make the build/docs reproducible without trial-and-error.

Repro steps

1. Clone this repo.
2. Try gcc -o config-pin ./tools/pmunts_muntsos/config-pin.c as suggested by books/beaglebone-cookbook/06iot/iot.rst.
3. Observe that tools/pmunts_muntsos/config-pin.c does not exist until you run tools/pmunts_muntsos/grab_latest.sh which fetches it from upstream.

Suggested fixes

• Add a short README in tools/pmunts_muntsos/README.md explaining how to run grab_latest.sh to obtain config-pin.c, or
• Update the Makefile to call grab_latest.sh automatically when attempting to build config-pin, or
• Update the docs (e.g., books/beaglebone-cookbook/06iot/iot.rst) to show the fetch step before the gcc command.

Notes

• This is a docs/build reproducibility issue that does not require hardware to verify. I'm happy to open a small PR that updates the docs and/or adds the README explaining the fetch step if maintainers agree.

[RobertCNelson]

@immortal71 this repo is dead, config-pin.c with later charges was moved to a different repo