fix: clarify disable examples per review feedback

Remove duplicate env var in keepalive example, use inline comment
instead. Explicitly state "set to -1" in the infinite connections note.

Author: ankurs

config-reference.md

@@ -69,7 +69,7 @@ cfg := config.GetColdBrewConfig()
 | `GRPC_SERVER_MAX_CONNECTION_AGE_IN_SECONDS` | int | `1800` | Maximum connection lifetime with ±10% jitter. Set to `-1` to disable this limit |
 | `GRPC_SERVER_MAX_CONNECTION_AGE_GRACE_IN_SECONDS` | int | `30` | Grace period after max connection age before force-closing. Set to `-1` to disable this limit |
 
-To allow connections to remain open indefinitely, disable both `GRPC_SERVER_MAX_CONNECTION_IDLE_IN_SECONDS` and `GRPC_SERVER_MAX_CONNECTION_AGE_IN_SECONDS`.
+To allow connections to remain open indefinitely, set both `GRPC_SERVER_MAX_CONNECTION_IDLE_IN_SECONDS` and `GRPC_SERVER_MAX_CONNECTION_AGE_IN_SECONDS` to `-1`.
 
 ## HTTP Gateway
 

howto/production.md

@@ -435,11 +435,9 @@ env:
   - name: GRPC_SERVER_MAX_CONNECTION_IDLE_IN_SECONDS
     value: "600"
   # Override: force connection refresh every hour instead of 30 minutes
+  # Change to "-1" to disable the connection age limit entirely (not recommended)
   - name: GRPC_SERVER_MAX_CONNECTION_AGE_IN_SECONDS
     value: "3600"
-  # Disable connection age limit entirely (not recommended)
-  # - name: GRPC_SERVER_MAX_CONNECTION_AGE_IN_SECONDS
-  #   value: "-1"
 ```
 
 ## Production checklist