[Fix] markdownlint errors in rule documentation

Author: sjarva

docs/rules/no-unknown-property.md

@@ -56,24 +56,23 @@ var AtomPanel = <atom-panel class="foo"></atom-panel>;
 - `enabled`: for enabling the rule. 0=off, 1=warn, 2=error. Defaults to 0.
 - `ignore`: optional array of property and attribute names to ignore during validation.
 
-
 If you are using a library that passes something as a prop to JSX elements, it is recommended to add those props to the ignored properties.
 
 For example, if you use [emotion](https://emotion.sh/docs/introduction) and its [`css` prop](https://emotion.sh/docs/css-prop)),
 add the following to your `.eslintrc` config file:
+
 ```js
 ...
 "react/no-unknown-property": ['error', { ignore: ['css'] }]
 ...
-
 ```
 
 Now, the following code passes:
+
 ```js
 var StyledDiv = <div css={{color: 'pink'}}></div>
 ```
 
-
 ## When Not To Use It
 
 If you are not using JSX you can disable this rule.