[minor][cdc][docs] Optimize markdown styles in quickstart doc

docs/content/docs/get-started/quickstart/mysql-to-doris.md

@@ -247,9 +247,9 @@ We can find that tables are created and inserted through Doris Web UI.
 ### Synchronize Schema and Data changes
 Enter MySQL container
 
-    ```shell
-    docker-compose exec mysql mysql -uroot -p123456
-    ```
+ ```shell
+ docker-compose exec mysql mysql -uroot -p123456
+ ```
 
 Then, modify schema and record in MySQL, and the tables of Doris will change the same in real time：
 1. insert one record in `orders` from MySQL:   

docs/content/docs/get-started/quickstart/mysql-to-starrocks.md

@@ -215,9 +215,9 @@ Connect to jdbc through database connection tools such as Dbeaver using `mysql:/
 ### Synchronize Schema and Data changes
 Enter MySQL container
 
-    ```shell
-    docker-compose exec mysql mysql -uroot -p123456
-    ```
+ ```shell
+ docker-compose exec mysql mysql -uroot -p123456
+ ```
 
 Then, modify schema and record in MySQL, and the tables of StarRocks will change the same in real time：
 1. insert one record in `orders` from MySQL: