README: point to new source location
flasher: heimdall-bootimg: add support for '--no-reboot' and '--resume'
helpers/envkernel.fish: add deactivate & reactivate function for fish
The pmbootstrap repository has been moved: https://postmarketos.org/source-code/
Related blog post: https://postmarketos.org/blog/2024/01/17/moving-pmbootstrap/