update readme

Example for 2.x or 3.x or 4.x please see tags in `https://github.com/apache/incubator-shardingsphere-example/tree/${tag}`

**Need attention**

- *Please do not use `dev` branch to run your example, example of `dev` branch is not released yet.*

- *The manual schema initial script is in `https://github.com/apache/incubator-shardingsphere-example/blob/dev/src/resources/manual_schema.sql`, please execute it before you first run the example.*

- *Please make sure master-slave data sync on MySQL is running correctly. Otherwise this example will query empty data from slave.*

## Before start the example

please make sure some dependencies from [shardingsphere](https://github.com/apache/incubator-shardingsphere) and [shardingsphere-spi-impl](https://github.com/OpenSharding/shardingsphere-spi-impl) have been installed since some examples depend on that.

## Before start the example if you want use `dev` branch

Please make sure some dependencies from [shardingsphere](https://github.com/apache/incubator-shardingsphere) and [shardingsphere-spi-impl](https://github.com/OpenSharding/shardingsphere-spi-impl) have been installed since some examples depend on that.

if you are a newbie for shardingsphere, you could prepare the dependencies as following: 

1.download and install [shardingsphere](https://github.com/apache/incubator-shardingsphere): 

```bash

## download the code of shardingsphere

git clone https://github.com/apache/incubator-shardingsphere.git

## checkout a specific version, say 4.0.0-RC1

## checkout a specific version, example is 4.0.0-RC1

cd incubator-shardingsphere && git checkout 4.0.0-RC1

## install the dependencies

mvn clean install -Prelease

mvn clean install

```

2.download and install [shardingsphere-spi-impl](https://github.com/OpenSharding/shardingsphere-spi-impl): 

```bash

## download the code of shardingsphere-spi-impl

git clone https://github.com/OpenSharding/shardingsphere-spi-impl.git

## checkout a specific version, say 4.0.0-RC1

## checkout a specific version, example is 4.0.0-RC1

cd shardingsphere-spi-impl && git checkout 4.0.0-RC1

## install the dependencies

mvn clean install

```

## sharding-sphere-example module design

## shardingsphere-example module design

### project structure

### project module

```

sharding-sphere-example

shardingsphere-example

  ├── example-common

  │   ├── config-utility

  │   ├── repository-api

  │   │   └── orchestration-spring-namespace-example

  │   ├── transaction-example

  │   │   ├── transaction-2pc-xa-example

  │   │   ├── transaction-base-saga-example

  │   │   └──transaction-base-seata-example

  │   ├── other-feature-example

  │   │   ├── hint-example

```

### Best practice for sharding data

* sharding databases

* sharding tables

* sharding databases and tables

* master-slave

* sharding & master-slave

you can get more detail from **[sharding-example](./sharding-jdbc-example/sharding-example)**

You can get more detail from **[sharding-example](./sharding-jdbc-example/sharding-example)**

### Best practice for sharding + orchestration

* local zookeeper/etcd & sharding

    local sharding configuration can override the configuration of zookeeper/etcd.

* cloud zookeeper/etcd & sharding

    shardingsphere will load the sharding configuration form zookeeper/etcd directly.

* using local configuration file for zookeeper/etcd & sharding

* using register center(zookeeper/etcd)'s configuration for sharding

you can get more detail from **[orchestration-example](./sharding-jdbc-example/orchestration-example)**

You can get more detail from **[orchestration-example](./sharding-jdbc-example/orchestration-example)**

### Best Practice for sharding + distribution-transaction

* 2pc-xa transaction

* base-saga transaction

* base-seata transaction

You can get more detail from **[transaction-example](./sharding-jdbc-example/transaction-example)**

### Best Practice for hint routing

You can get more detail from **[hint-example](./sharding-jdbc-example/other-feature-example/hint-example)**

### Best Practice for broadcast table

You can get more detail from **[broadcast-table-example](./sharding-jdbc-example/other-feature-example/broadcast-table-example)**

you can get more detail from **[transaction-example](./sharding-jdbc-example/transaction-example)**

### Best Practice for data encrypt

### how to use hint routing

you can get more detail from **[hint-example](./sharding-jdbc-example/other-feature-example/hint-example)**

You can get more detail from **[encrypt-example](./sharding-jdbc-example/other-feature-example/encrypt-example)**

### how to config broadcast-table

you can get more detail from **[broadcast-table-example](./sharding-jdbc-example/other-feature-example/broadcast-table-example)**

### Best Practice for APM

### how to encrypt & decrypt data in shardingsphere

you can get more detail from **[encrypt-example](./sharding-jdbc-example/other-feature-example/encrypt-example)**

We will add APM example recently.

### how to use APM with shardingsphere

we will add APM example recently.

### Best Practice for sharding-proxy.

### how to use sharding-proxy with jdbc.

we prefer to add a docker base example recently.

We prefer to add a docker base example recently.

### [how to use docker to config sharding-jdbc & sharding-proxy](./docker/docker-compose.md) (Optional)