Update opendal.h

Signed-off-by: Xuanwo <[email protected]>

bindings/c/include/opendal.h

@@ -96,15 +96,17 @@ typedef struct BlockingLister BlockingLister;
  *
  * # Examples
  *
+ * ## Init backends
+ *
  * Read more backend init examples in [`services`]
  *
  * ```
  * # use anyhow::Result;
  * use opendal::services::Fs;
  * use opendal::BlockingOperator;
  * use opendal::Operator;
- * #[tokio::main]
- * async fn main() -> Result<()> {
+ *
+ * fn main() -> Result<()> {
  *     // Create fs backend builder.
  *     let mut builder = Fs::default();
  *     // Set the root for fs, all operations will happen under this root.
@@ -118,6 +120,35 @@ typedef struct BlockingLister BlockingLister;
  *     Ok(())
  * }
  * ```
+ *
+ * ## Init backends with blocking layer
+ *
+ * Some services like s3, gcs doesn't have native blocking supports, we can use [`layers::BlockingLayer`]
+ * to wrap the async operator to make it blocking.
+ *
+ * ```rust
+ * # use anyhow::Result;
+ * use opendal::layers::BlockingLayer;
+ * use opendal::services::S3;
+ * use opendal::BlockingOperator;
+ * use opendal::Operator;
+ *
+ * #[tokio::main]
+ * async fn main() -> Result<()> {
+ *     // Create fs backend builder.
+ *     let mut builder = S3::default();
+ *     builder.bucket("test");
+ *     builder.region("us-east-1");
+ *
+ *     // Build an `BlockingOperator` with blocking layer to start operating the storage.
+ *     let _: BlockingOperator = Operator::new(builder)?
+ *         .layer(BlockingLayer::create()?)
+ *         .finish()
+ *         .blocking();
+ *
+ *     Ok(())
+ * }
+ * ```
  */
 typedef struct BlockingOperator BlockingOperator;