index.md: add '2025 - Linux Foundation Member Summit - Ronald (Ron) Minnich - Deploying Linux as Firmware at Global Scale: Update' presentation paper

This unrecorded conference: https://lfms25.sched.com/event/1urX2/deploying-linux-as-firmware-at-global-scale-update-ronald-minnich-hewlett-packard PDF saved through https://github.com/linuxboot/heads-wiki/issues/191 Closes #191 TODO: maybe switch to archive.org but wasn't able to save archive of it and archive.as same story.