Update themes.mdx

Co-authored-by: Hahnbee Lee <[email protected]>

Author: baell

themes.mdx

@@ -10,7 +10,7 @@ We offer pre-built themes so you can differentiate the look and feel of your doc
 
 ## Configuration
 
-You can configure the theme in the `docs.json` file by referencing the theme name.
+You can configure the theme in the `docs.json` file by setting the `theme` property.
 
 For example, to use the `maple` theme, you can add the following to your `docs.json` file: