Update security policy file

SECURITY.md

@@ -21,10 +21,5 @@ To report security issues in the Nano protocol, please send an email to security
 | GitHub Username | Email | GPG Pubkey |
 |-----------------------|--------|-----------------|
 | [clemahieu](https://github.com/clemahieu) | clemahieu { at } gmail.com | [clemahieu.asc](https://github.com/nanocurrency/nano-node/blob/develop/etc/gpg/clemahieu.asc) |
-| [argakiig](https://github.com/argakiig) | russel { at } nano.org | [argakiig.asc](https://github.com/nanocurrency/nano-node/blob/develop/etc/gpg/argakiig.asc) |
-| [sergiysw](https://github.com/sergiysw) | sergiysw { at } gmail.com | [sergiysw.asc](https://github.com/nanocurrency/nano-node/blob/develop/etc/gpg/sergiysw.asc) |
-| [zhyatt](https://github.com/zhyatt) | zach { at } nano.org | [zhyatt.asc](https://github.com/nanocurrency/nano-node/blob/develop/etc/gpg/zhyatt.asc) |
 
 For details on how to send a GPG encrypted email, see the tutorial here: https://www.linode.com/docs/security/encryption/gpg-keys-to-send-encrypted-messages/.
-
-For general support and other non-sensitive inquiries, please visit https://forum.nano.org.