Minor Markdown consistency cleanup. (#24605)

docs/4.0/getting-started/webpack.md

@@ -56,6 +56,7 @@ Notice that if you chose to **import plugins individually**, you must also insta
 To enjoy the full potential of Bootstrap and customize it to your needs, use the source files as a part of your project's bundling process.
 
 First, create your own `_custom.scss` and use it to override the [built-in custom variables]({{ site.baseurl }}/docs/{{ site.docs_version }}/getting-started/options/). Then, use your main sass file to import your custom variables, followed by Bootstrap:
+
 {% highlight scss %}
 @import "custom";
 @import "~bootstrap/scss/bootstrap";