[hotfix][docs] Fix the abnormal display of pictures (#2513)

docs/content/about.md

@@ -298,21 +298,21 @@ The dependencies are now available in your local `.m2` repository.
 2. Fork Flink CDC project to your GitHub repositories
    ![fork](/_static/fig/contribute_guidance/fork.png "fork")
 3. Clone and compile your Flink CDC project
-```bash
-git clone https://github.com/your_name/flink-cdc-connectors.git
-cd flink-cdc-connectors
-mvn clean install -DskipTests
-```
+    ```bash
+    git clone https://github.com/your_name/flink-cdc-connectors.git
+    cd flink-cdc-connectors
+    mvn clean install -DskipTests
+    ```
 4. Check to a new branch and start your work
-```bash
-git checkout -b my_feature
--- develop and commit
-```
-![check_branch](/_static/fig/contribute_guidance/check_branch.png "check_branch")
+    ```bash
+   git checkout -b my_feature
+   -- develop and commit
+    ```
+   ![check_branch](/_static/fig/contribute_guidance/check_branch.png "check_branch")
 5. Push your branch to your github
-```bash
-git push origin my_feature
-```
+    ```bash
+   git push origin my_feature
+    ```
 6. Open a PR to https://github.com/ververica/flink-cdc-connectors
    ![open_pr](/_static/fig/contribute_guidance/open_pr.png "open_pr")