fix markdown code block

docs/layout.md

@@ -6,7 +6,7 @@ Take a new layout named `secondary` as an example to make the route starting wit
 
 1. Add related configuration in `src/utils/config.js`. For details, please refer to [layouts](/configuration?id=layouts).
 
-   ```javascript
+```javascript
    layouts: [
            {
                name: 'primary',
@@ -18,11 +18,11 @@ Take a new layout named `secondary` as an example to make the route starting wit
                include: [/(\/(en|zh))*\/seconday\/(.*)/],
            },
    ],
-   ```
+```
 
 2. Add the `secondary` layout component to the `src/layouts/BaseLayout.js` file.
 
-   ```javascript
+```javascript
    import SecondaryLayout from './SecondaryLayout'
 
    const LayoutMap = {
@@ -30,11 +30,11 @@ Take a new layout named `secondary` as an example to make the route starting wit
      Public: PublicLayout,
      Secondary: SecondaryLayout,
    }
-   ```
+```
 
 3. Add the `SecondaryLayout.js` file to the `src/layouts/` directory.
 
-   ```javascript
+```javascript
    import React from 'react'
 
    export default ({ children }) => {
@@ -45,16 +45,16 @@ Take a new layout named `secondary` as an example to make the route starting wit
        </div>
      )
    }
-   ```
+```
 
 4. Add a `seconday/index.js` file to the `src/pages/` directory.
 
-   ```javascript
+```javascript
    import React from 'react'
 
    export default ({ children }) => {
      Return <div>Seconday page Content</div>
    }
-   ```
+```
 
-5. Finally, start the development mode `npm run start`, open [http://localhost:7000/seconday/](http://localhost:7000/seconday/) and you will see the page for the `seconday` layout.
+5. Finally, start the development mode `npm run start`, open [http://localhost:7000/seconday/](http://localhost:7000/seconday/) and you will see the page for the `seconday` layout.