Switch `--preserve-live-mode` and config `live_mode` not documented in README.md

[Leonardo Rochael Almeida]

Distribution (run cat /etc/os-release):

NAME="Pop!_OS"
VERSION="22.04 LTS"
ID=pop
ID_LIKE="ubuntu debian"
PRETTY_NAME="Pop!_OS 22.04 LTS"
VERSION_ID="22.04"
HOME_URL="https://pop.system76.com"
SUPPORT_URL="https://support.system76.com"
BUG_REPORT_URL="https://github.com/pop-os/pop/issues"
PRIVACY_POLICY_URL="https://system76.com/privacy"
VERSION_CODENAME=jammy
UBUNTU_CODENAME=jammy
LOGO=distributor-logo-pop-os

Related Application and/or Package Version (run apt policy $PACKAGE NAME):

kernelstub:
  Installed: 3.1.4~1674849051~22.04~851230b
  Candidate: 3.1.4~1674849051~22.04~851230b
  Version table:
 *** 3.1.4~1674849051~22.04~851230b 1001
       1001 http://apt.pop-os.org/release jammy/main amd64 Packages
       1001 http://apt.pop-os.org/release jammy/main i386 Packages
        100 /var/lib/dpkg/status

Issue/Bug Description:

In the README.md file in the repo as of now, the table of options in the Usage section doesn't document the --preserve-live-mode option, or its equivalent live_mode configuration in the file.

Steps to reproduce (if you know):

Read the README.md file.

Expected behavior:

The option and it's behavior should be documented.

Other Notes:

By the way, the README.md file should be present in the installed Debian package at /usr/share/doc/README.md. Right now its nowhere in the system.

And speaking of files in the installed Debian package, at least in the above-mentioned 3.1.4 version, the sample configuration file is at /etc/default/kernelstub.SAMPLE, not at /etc/kernelstub/SAMPLE as mentioned in the README.md file. It's location at /etc/default is baffling to me, since that is not a place to put sample configuration files. Rather /etc/default is a place to put parameters used by init scripts, which kernelstub, not running at boot, has no use for.

I guess the above paragraphs should be separate bugs, but anyone free to file them.