Add Warning to RxWorkers about Asynchrony

workflow-rx2/src/main/java/com/squareup/workflow1/rx2/RxWorkers.kt

@@ -19,6 +19,14 @@ import org.reactivestreams.Publisher
  * The [Observable] will be subscribed to when the [Worker] is started, and disposed when it is
  * cancelled.
  *
+ * Note that a [Worker] actually operates on a [kotlinx.coroutines.flow]. This means that your
+ * [Observable] will first be adapted to a flow. To do this a communication structure is used
+ * that will mean that the flow will process the items produced by the [Observable] asynchronously.
+ *
+ * Note that this [Observable] is transformed to a backpressure aware [Flowable] using the
+ * [BUFFER] strategy before being transformed to a flow, which means that buffering will happen
+ * in the [Flowable] before being passed over to the flow if it is experiencing backpressure.
+ *
  * RxJava doesn't allow nulls, but it can't express that in its types. The receiver type parameter
  * is nullable so that the resulting [Worker] is non-nullable instead of having
  * platform nullability.
@@ -32,6 +40,10 @@ public inline fun <reified T : Any> Observable<out T?>.asWorker(): Worker<T> =
  * The [Publisher] will be subscribed to when the [Worker] is started, and cancelled when it is
  * cancelled.
  *
+ * Note that a [Worker] actually operates on a [kotlinx.coroutines.flow]. This means that your
+ * [Publisher] will first be mapped to a flow. To do this a communication structure is used
+ * that will mean that the flow will process the items produced by the [Publisher] asynchronously.
+ *
  * RxJava doesn't allow nulls, but it can't express that in its types. The receiver type parameter
  * is nullable so that the resulting [Worker] is non-nullable instead of having
  * platform nullability.