gall: fix issue id in comment
The comment was pointing at the wrong GitHub issue.
attributing.agent-routes :: guest
agent-name :: agent
== ::
- :* :: NB (jtobin): see urbit/urbit#1620
+ :* :: NB (jtobin): see urbit/urbit#1466
wex=~ :: outgoing
sup=incoming.subscribers.current-agent :: incoming
== ::
