docs: clarify ready endpoint checks for fully hydrated cache

Co-Authored-By: Tejas Badadare <[email protected]>

Author: devin-ai-integration[bot]

apps/hermes/server/src/api/rest/ready.rs

@@ -8,6 +8,15 @@ use {
     },
 };
 
+/// Endpoint that returns OK (200) only when the cache is fully hydrated.
+/// 
+/// The cache is considered fully hydrated when all of the following conditions are met:
+/// - `has_completed_recently`: The latest completed update is recent (within the staleness threshold)
+/// - `is_not_behind`: The latest completed slot isn't too far behind the latest observed slot
+/// - `is_metadata_loaded`: Price feeds metadata is not empty
+///
+/// If any of these conditions are not met, the endpoint returns SERVICE_UNAVAILABLE (503)
+/// along with detailed metadata about the readiness state.
 pub async fn ready<S>(State(state): State<ApiState<S>>) -> Response
 where
     S: Aggregates,