docs: point rpm-ostree users at the working acpi-fix method

[Weijtmans]

Closes #48.

The ACPI fix's Step 2 offers Fedora (BLS) or Arch/Debian (GRUB) instructions, and a Bazzite user following the Fedora branch lands in an empty nano buffer, which is exactly what #48 reports: an ostree system has no /boot/loader/entries/<machine-id>-<kernel>.conf, its BLS entries are regenerated ostree-*.conf files, and hand edits there do not survive the next deployment.

The working method for that family was already on this site, on the Fedora CoreOS page (dracut override directory plus rpm-ostree initramfs --enable), but nothing linked to it. This PR:

• adds an "On Bazzite, Fedora Atomic and other rpm-ostree distros" variant to Step 2 of the governor page's ACPI section, summarizing the CoreOS page's method (with credit and a link) and explaining why the plain-Fedora command opens an empty file,
• extends the Kernel Update Note: the rpm-ostree method is not affected, since the initramfs is regenerated with the tables on every deployment,
• gives linux/bazzite.md a short ACPI section under Post-Installation Configuration pointing at the right variant, so Bazzite readers stop guessing between the two existing branches.

The method itself is the one already documented and verified on the CoreOS page; this change connects it to the audience that keeps missing it.

mkdocs build --strict passes.

[tfabris]

I followed the steps in the PR, typing these commands:

sudo mkdir -p /etc/dracut.conf.d/acpi/
sudo cp bc250-acpi-fix/*.aml /etc/dracut.conf.d/acpi/
sudo tee /etc/dracut.conf.d/99-acpi-override.conf <<'CONF'
acpi_override="yes"
acpi_table_dir="/etc/dracut.conf.d/acpi"
CONF
sudo rpm-ostree initramfs --enable
sudo systemctl reboot

And they seemed to succeed, but then the PR also says to do this:

After the reboot, `dmesg | grep SSDT` should report both tables found in the initrd, as shown on the CoreOS page.

That command resulted in:

dmesg: read kernel buffer failed: Operation not permitted

I believe it needs a "sudo" in front of it, after I added "sudo" I think I see these lines in the output which is, I believe, what we were looking for:

[    0.005570] ACPI: SSDT ACPI table found in initrd [kernel/firmware/acpi/SSDT-CST.aml][0x30e]
[    0.005572] ACPI: SSDT ACPI table found in initrd [kernel/firmware/acpi/SSDT-PST.aml][0x39e]