[docs][cdc-connector][oceanbase] update docker image and os compatibility in quickstart (apache#2897)

* [docs][cdc-connector] update docker image and description in oceanbase quickstart

* revert removal by accident

Author: whhe

docs/content/quickstart/oceanbase-tutorial.md

@@ -11,15 +11,20 @@
 
 Create `docker-compose.yml`.
 
+*Note*: `host` network mode is required in this demo, so it can only work on Linux, see [network-tutorial-host](https://docs.docker.com/network/network-tutorial-host/).
+
 ```yaml
 version: '2.1'
 services:
   observer:
-    image: oceanbase/oceanbase-ce:4.0.0.0
+    image: oceanbase/oceanbase-ce:4.2.0.0
     container_name: observer
+    environment:
+      - 'MODE=slim'
+      - 'OB_ROOT_PASSWORD=pswd'
     network_mode: "host"
   oblogproxy:
-    image: whhe/oblogproxy:1.1.0_4x
+    image: whhe/oblogproxy:1.1.3_4x
     container_name: oblogproxy
     environment:
       - 'OB_SYS_USERNAME=root'
@@ -60,20 +65,6 @@ docker-compose up -d
 
 ### Set password
 
-There is no password for 'root' user by default, but we need a user of 'sys' tenant with non-empty password in oblogproxy. So here we should set a password for 'root@sys' firstly.
-
-Login 'root' user of 'sys' tenant.
-
-```shell
-docker-compose exec observer obclient -h127.0.0.1 -P2881 -uroot@sys
-```
-
-Set a password, note that the password needs to be consistent with the environment variable 'OB_SYS_PASSWORD' of oblogproxy service.
-
-```mysql
-ALTER USER root IDENTIFIED BY 'pswd';
-```
-
 From OceanBase 4.0.0.0 CE, we can only fetch the commit log of non-sys tenant.
 
 Here we use the 'test' tenant for example.

docs/content/快速上手/oceanbase-tutorial-zh.md

@@ -12,15 +12,20 @@
 
 配置 `docker-compose.yml`。
 
+*注意*：本示例需要使用`host`网络，所以只能在 Linux 系统上运行，更多信息见 [network-tutorial-host](https://docs.docker.com/network/network-tutorial-host/)。
+
 ```yaml
 version: '2.1'
 services:
   observer:
-    image: oceanbase/oceanbase-ce:4.0.0.0
+    image: oceanbase/oceanbase-ce:4.2.0.0
     container_name: observer
+    environment:
+      - 'MODE=slim'
+      - 'OB_ROOT_PASSWORD=pswd'
     network_mode: "host"
   oblogproxy:
-    image: whhe/oblogproxy:1.1.0_4x
+    image: whhe/oblogproxy:1.1.3_4x
     container_name: oblogproxy
     environment:
       - 'OB_SYS_USERNAME=root'
@@ -61,20 +66,6 @@ docker-compose up -d
 
 ### 设置密码
 
-OceanBase 中 root 用户默认是没有密码的，但是 oblogproxy 需要配置一个使用非空密码的系统租户用户，因此这里我们需要先为 root@sys 用户设置一个密码。
-
-登陆 sys 租户的 root 用户：
-
-```shell
-docker-compose exec observer obclient -h127.0.0.1 -P2881 -uroot@sys
-```
-
-设置密码，注意这里的密码需要与上一步中 oblogproxy 服务的环境变量 'OB_SYS_PASSWORD' 保持一样。
-
-```mysql
-ALTER USER root IDENTIFIED BY 'pswd';
-```
-
 OceanBase 从社区版 4.0.0.0 开始只支持对非 sys 租户的增量数据拉取，这里我们使用 test 租户的 root 用户作为示例。
 
 登陆 test 租户的 root 用户：