docs: admin: devices: /dev/sr<N> for SCSI CD-ROM

Don't claim that /dev/sr<N> device names for SCSI CD-ROM drives are
deprecated and don't recommend /dev/scd<N> alternate names for them.

/dev/scd<N> device names for SCSI CD-ROM drives are not in use for more
than a decade, see commit [1] that was a part of udev release 174.
Earlier, related rules were volatile, sometimes /dev/scd<N> were syminks
to /dev/sr<N>, sometimes vice versa.

Recognizing of root=/dev/scd<N> kernel command line argument was removed
in kernel 2.5.45 [2].

In the docs /dev/scd<N> became recommended names in 2.6.9 [3].
Mention of these names appeared much earlier in 1.3.22 [4].

[1] https://git.kernel.org/pub/scm/linux/hotplug/udev.git/commit/?id=d132be4d58
2011-08-12 14:05:19 +0200 Kay Sievers.
rules: remove legacy rules for cdrom and usb printer

[2] https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/init?h=v2.5.45&id=51924607bd
2002-10-29 00:47:58 -0800 Alexander Viro.
[PATCH] removal of root_dev_names[]

[3] https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/diff/Documentation/devices.txt?h=v2.6.9-rc4&id=a74e11ffeda
2004-03-16 15:09:38 -0800 Andrew Morton:
[PATCH] devices.txt: typos and removal of dead devices

[4] https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/tree/Documentation/devices.txt?h=v2.6.9-rc4&id=8f0ec1f9369
1995-09-01 Linus Torvalds: Import 1.3.22

Signed-off-by: Max Nikulin <manikulin@gmail.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <f0a3e0aa-e4f9-41d3-8931-57837831d136@gmail.com>