Clarify `own_key` scheme

[Powersource]

https://github.com/ssbc/private-group-spec/tree/master/direct-messages#b-self-case---mapping-our-own-feed_id-to-recp_key

That section says

the full key you try with a slot is of form { key, scheme: "envelope-symmetric-key-for-self" }

but it also says

The complete key-and-scheme for the envelope key_recp slot is of form js { key: Buffer, // the directMessageSlotKey scheme: "envelope-id-based-dm-converted-ed25519" }

that's confusing to me but the second one looks like it might be accidentally included from copy pasting some other section. Is the first one correct and is it fine to remove the second one?