Add UTM tags to the preview site badge (#3277)

Author: addisonschultz

README.md

@@ -150,11 +150,11 @@ See `LICENSE` for more information.
 </p>
 
 ```md
-[![GitBook](https://img.shields.io/static/v1?message=Documented%20on%20GitBook&logo=gitbook&logoColor=ffffff&label=%20&labelColor=5c5c5c&color=3F89A1)](https://gitbook.com/)
+[![GitBook](https://img.shields.io/static/v1?message=Documented%20on%20GitBook&logo=gitbook&logoColor=ffffff&label=%20&labelColor=5c5c5c&color=3F89A1)](https://www.gitbook.com/preview?utm_source=gitbook_readme_badge&utm_medium=organic&utm_campaign=preview_documentation&utm_content=link)
 ```
 
 ```html
-<a href="https://gitbook.com">
+<a href="https://www.gitbook.com/preview?utm_source=gitbook_readme_badge&utm_medium=organic&utm_campaign=preview_documentation&utm_content=link">
     <img
         src="https://img.shields.io/static/v1?message=Documented%20on%20GitBook&logo=gitbook&logoColor=ffffff&label=%20&labelColor=5c5c5c&color=3F89A1"
     />