Document most missing options

Document most missing options

Add cmd-nits make target.

Listing options should stop when it hits the "parameters" separator.

Add missing .pod.in files to doc/man1/build.info

Tweak find-doc-nits to try openssl-XXX before XXX for POD files and
change an error messavge to be more useful.

Fix the following pages: ca, cms, crl, dgst, enc,
engine, errstr, gendsa, genrsa, list, ocsp, passwd, pkcs7, pkcs12, rand,
rehash, req, rsautil, s_server, speed, s_time,
sess_id, smime, srp, ts, x509.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/10873)