tailcfg: document SSHPrincipal.PubKeys URL expansions
From which lacked docs.
Updates
@@ -1706,6 +1706,10 @@ type SSHPrincipal struct {
//
// As a special case, if len(PubKeys) == 1 and PubKeys[0] starts
// with "https://", then it's fetched (like https://github.com/username.keys).
+ // In that case, the following variable expansions are also supported
+ // in the URL:
+ // * $LOGINNAME_EMAIL ("foo@bar.com" or "foo@github")
+ // * $LOGINNAME_LOCALPART (the "foo" from either of the above)
PubKeys []string `json:"pubKeys,omitempty"`
}
