New comment by NeelChotai on void-packages repository

https://github.com/void-linux/void-packages/pull/29098#issuecomment-787144742

Comment:
> I think it would be reasonable to move the entire contents of this to README.voidlinux and make the install message nothing more than
> 
> > See /usr/share/doc/efibootmgr/README.voidlinux for instructions on using efibootmgr to automatically manage EFI boot entries.
> 
> I believe `/sys/firmware/efi/efivars` might automatically mounted by elogind for some reason. Systems without elogind probably need to mount it explicitly.

That explains it, and your suggestion sounds good - implemented.