docs: async and sync method comments (#465)

Author: stainless-app[bot]

lithic-java-core/src/main/kotlin/com/lithic/api/client/LithicClient.kt

@@ -50,6 +50,12 @@ import com.lithic.api.services.blocking.WebhookService
  */
 interface LithicClient {
 
+    /**
+     * Returns a version of this client that uses asynchronous execution.
+     *
+     * The returned client shares its resources, like its connection pool and thread pools, with
+     * this client.
+     */
     fun async(): LithicClientAsync
 
     fun accounts(): AccountService

lithic-java-core/src/main/kotlin/com/lithic/api/client/LithicClientAsync.kt

@@ -51,6 +51,12 @@ import java.util.concurrent.CompletableFuture
  */
 interface LithicClientAsync {
 
+    /**
+     * Returns a version of this client that uses synchronous execution.
+     *
+     * The returned client shares its resources, like its connection pool and thread pools, with
+     * this client.
+     */
     fun sync(): LithicClient
 
     fun accounts(): AccountServiceAsync