Function advertise_as 

pub fn advertise_as(
    identity: &NodeIdentity,
    runtime: &str,
    seq: u64,
    endpoints: &[String],
    caps: &[String],
    repos: &[String],
    version: &str,
) -> Envelope

Build and sign the advertisement of one runtime of this node.

use majordomus_cli::mesh::identity::NodeIdentity;
use majordomus_cli::mesh::protocol::{advertise_as, encode, parse};
let node = NodeIdentity::ephemeral().unwrap();
let envelope = advertise_as(&node, "00000000000000aa", 1, &[], &[], &[], "docs");
assert_eq!(parse(&encode(&envelope).unwrap()).unwrap().adv.rt, "00000000000000aa");