Document backpressure options on read and subscription (#345)

Co-authored-by: William Chong <william-chong@outlook.com>

Author: github-actions[bot]

docs/api/reading-events.md

@@ -385,4 +385,17 @@ publisher.subscribe(new Subscriber<ReadMessage>() {
 
 latch.await();
 ```
-:::
+:::
+
+## Configuring Backpressure
+
+The client allows you to configure backpressure to control how many events are buffered on the client side before requesting more from the server.
+
+| Option         | Description                                                                 | Default Value |
+|----------------|-----------------------------------------------------------------------------|---------------|
+| batchSize      | The maximum number of events the client will request from the server in a single batch. | 512           |
+| thresholdRatio | The fraction of the `batchSize` at which the client will send a new request for more events. | 0.25          |
+
+By default, the client requests up to 512 events at a time. It will automatically
+request more events when the number of buffered (unprocessed) events falls below
+25% of the batch size.

docs/api/subscriptions.md

@@ -406,3 +406,16 @@ For example:
 - If `n` = 2, the notification is sent every 64 events.
 - If `n` = 3, it is sent every 96 events, and so on.
 :::
+
+## Configuring Backpressure
+
+The client allows you to configure backpressure to control how many events are buffered on the client side before requesting more from the server.
+
+| Option         | Description                                                                 | Default Value |
+|----------------|-----------------------------------------------------------------------------|---------------|
+| batchSize      | The maximum number of events the client will request from the server in a single batch. | 512           |
+| thresholdRatio | The fraction of the `batchSize` at which the client will send a new request for more events. | 0.25          |
+
+By default, the client requests up to 512 events at a time. It will automatically
+request more events when the number of buffered (unprocessed) events falls below
+25% of the batch size.