Consistent formatting of flags with args

Consistent formatting of flags with args

For documentation of all commands with "-flag arg" format them
consistently: "B<-flag> I<arg>", except when arg is literal
(for example "B<-inform> B<PEM>|B<DER>")
Update find-doc-nits to complain if badly formatted strings are found.

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10022)