doc: clarify -cipher option syntax in man pages

doc: clarify -cipher option syntax in man pages

Users reading the documentation for the -<cipher> option often
misunderstand the syntax. The notation "B<-I<cipher>>" renders as
"-cipher" with "cipher" in italics, leading users to think they
should type "-cipher aes-128-cbc" when the correct usage is
"-aes-128-cbc" (the cipher name directly as the option).

Update the documentation in openssl-genpkey, openssl-enc, and
openssl-pkey to explicitly state that the cipher name is prepended
with a hyphen and used directly as the option, not as an argument
to a "-cipher" flag.

Also add a reference to "openssl list -cipher-algorithms" to help
users discover available ciphers, and fix a typo in openssl-pkey
("and and" -> "and").

Fixes #26089

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Frederik Wedel-Heinen <fwh.openssl@gmail.com>
MergeDate: Fri Feb 13 14:52:00 2026
(Merged from https://github.com/openssl/openssl/pull/29843)