reorganization of _examples and add some new examples such as iris+groupcache+mysql+docker

Former-commit-id: ed635ee95de7160cde11eaabc0c1dcb0e460a620

_examples/kafka-api/README.md

@@ -0,0 +1,33 @@
+# Writing an API for Apache Kafka with Iris
+
+Read the [code](main.go).
+
+## Docker
+
+1. Open [docker-compose.yml](docker-compose.yml) and replace `KAFKA_ADVERTISED_HOST_NAME` with your own local address
+2. Install [Docker](https://www.docker.com/)
+3. Execute the command below to start kafka stack and the go application:
+
+```sh
+$ docker-compose up
+```
+
+## Manually
+
+Install & run Kafka and Zookeper locally and then:
+
+```sh
+go run main.go
+```
+
+## Screens
+
+![](0_docs.png)
+
+![](1_create_topic.png)
+
+![](2_list_topics.png)
+
+![](3_store_to_topic.png)
+
+![](4_retrieve_from_topic_real_time.png)