Update userguide/aviate/aviate-metering.adoc

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: sbrossie

userguide/aviate/aviate-metering.adoc

@@ -31,7 +31,7 @@ Refer to the https://docs.killbill.io/latest/userguide_configuration.html[__Kill
 
 Once the aviate plugin has been installed and the metering feature is enabled, you can start using the Aviate Metering APIs. These APIs enable creation of billing meters and allow to record raw (non aggregated) usage points. These APIs replace the https://killbill.github.io/slate/usage.html#record-usage-for-a-subscription[Kill Bill usage APIs]: Users should either use existing Kill Bill usage APIs (to record aggregated usage points) or use the Aviate metering APIs discussed in this section. For more details about these APIs, please refer to our https://apidocs.killbill.io/aviate-metering[api docs].
 
-Note that in the current implementation, the caller should ensure that all usage points for a specific subscription should be serialized.
+Note that in the current implementation, the caller should ensure that all usage points for a specific subscription are submitted sequentially (i.e., must not be submitted concurrently).
 
 == A Metering Example