Merge pull request #13758 from nemobis/federicol-remotewrite-tuning

[DOCS] Remote-Write: Clarify batch_send_deadline docs

docs/configuration/configuration.md

@@ -3673,7 +3673,8 @@ queue_config:
   [ min_shards: <int> | default = 1 ]
   # Maximum number of samples per send.
   [ max_samples_per_send: <int> | default = 2000]
-  # Maximum time a sample will wait in buffer.
+  # Maximum time a sample will wait for a send. The sample might wait less
+  # if the buffer is full. Further time might pass due to potential retries.
   [ batch_send_deadline: <duration> | default = 5s ]
   # Initial retry delay. Gets doubled for every retry.
   [ min_backoff: <duration> | default = 30ms ]