swarm-ui: name the subagent cap in the three descriptions that list inference fields

swarm-controller README, the swarmctl inference doc comment (and the
regenerated swarmctl-cli.md) and the hive-agent swarm_inference module doc
still listed only model, effort and subagent models.

hive-agent/src/swarm_inference.rs

@@ -20,7 +20,7 @@
 //! A failed read changes nothing. Until the first successful read after a
 //! start, the agent runs on its local values.
 //!
-//! `subagent_models` is not read here.
+//! `subagent_models` and `max_subagents` are not read here.
 
 use std::time::Duration;