docs: name the swarm display name by its new path

Two sites spelled it as a brace group, services.hyperhive.{hiveName,
swarmName}, which no anchored rewrite can handle correctly now that only
one of the two moves; both are written out separately. One of them is an
MCP tool description, so it is rendered into every agent's system prompt.

hive-agent/src/identity.rs

@@ -42,7 +42,7 @@ pub fn hive_name() -> Option<String> {
 /// Human display name of the wider swarm this hive belongs to (e.g.
 /// `constellat1on`). Federated hives at different DNS domains can
 /// share a swarm name. Returns None when the host-side
-/// `services.hyperhive.swarmName` option is unset.
+/// `services.hyperhive.swarm.name` option is unset.
 #[must_use]
 pub fn swarm_name() -> Option<String> {
     non_empty_env("HYPERHIVE_SWARM_NAME")