openssl-dgst.pod.in: Fix documentation of -list option
openssl-dgst.pod.in: Fix documentation of -list option

Mention openssl list -digest-algorithms, NOT -digest-commands.

Move option -list just after the related option -digest.

Fix HTML formatting of section 'Examples' by adding missing
newlines and add 2 examples variant to clarify syntax of the
command.

Reviewed-by: Paul Dale <ddec78389666b4f7c9b4d110380c848489a3e4aa@openssl.org>
Reviewed-by: Tomas Mraz <2bc6038c3dfca09b2da23c8b6da8ba884dc2dcc2@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17626)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl