Update cms docs.

[B<-secretkeyid id>]

[B<-econtent_type type>]

[B<-inkey file>]

[B<-keyopt name:parameter>]

[B<-passin arg>]

[B<-rand file(s)>]

[B<cert.pem...>]

for signing and encryption this option can be used multiple times to

set customised parameters for the preceding key or certificate. It can

currently be used to set RSA-PSS for signing or RSA-OAEP for encryption.

currently be used to set RSA-PSS for signing, RSA-OAEP for encryption

or to modify default parameters for ECDH.

=item B<-passin arg>

The B<-secretkey> option when used with B<-encrypt>.

The use of PSS with B<-sign>.

The use of OAEP or non-RSA keys with B<-encrypt>.

Additionally the B<-EncryptedData_create> and B<-data_create> type cannot

be processed by the older B<smime> command.

Create encrypted mail using RSA-OAEP:

 openssl cms -encrypt -in plain.txt -camellia128 -out mail.msg \

 openssl cms -encrypt -in plain.txt -out mail.msg \

	-recip cert.pem -keyopt rsa_padding_mode:oaep

Use SHA256 KDF with an ECDH certificate:

 openssl cms -encrypt -in plain.txt -out mail.msg \

	-recip ecdhcert.pem -keyopt ecdh_kdf_md:sha256

=head1 BUGS

The MIME parser isn't very clever: it seems to handle most messages that I've

Support for RSA-OAEP and RSA-PSS was first added to OpenSSL 1.1.0. 

The use of non-RSA keys with B<-encrypt> and B<-decrypt> was first added

to OpenSSL 1.1.0.

=cut