doc: Missing new ECDH algorithms in documentation

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

doc/mainpage.dox

@@ -19,7 +19,7 @@ the interesting functions as you go.
 
 The libssh library provides:
 
- - <strong>Key Exchange Methods</strong>: <i>curve25519-sha256@libssh.org, ecdh-sha2-nistp256</i>, diffie-hellman-group1-sha1, diffie-hellman-group14-sha1
+ - <strong>Key Exchange Methods</strong>: <i>curve25519-sha256@libssh.org, ecdh-sha2-nistp256, ecdh-sha2-nistp384, ecdh-sha2-nistp521</i>, diffie-hellman-group1-sha1, diffie-hellman-group14-sha1
  - <strong>Hostkey Types</strong>: <i>ecdsa-sha2-nistp256</i>, ssh-dss, ssh-rsa
  - <strong>Ciphers</strong>: <i>aes256-ctr, aes192-ctr, aes128-ctr</i>, aes256-cbc (rijndael-cbc@lysator.liu.se), aes192-cbc, aes128-cbc, 3des-cbc, blowfish-cbc, none
  - <strong>Compression Schemes</strong>: zlib, <i>zlib@openssh.com</i>, none