fix build error

Author: neoarz

docs/advanced/app-sources.mdx

@@ -15,7 +15,7 @@ You can create a link to automatically add your AltSource by using this template
 ```
 sidestore://source?url=[source url]
 ```
-For more info, see [URL Schema](advanced/url-schema). It is often helpful to create the link to your AltSource in this format, then put it into a link shortener such as ```tinyurl.com```. However, if a user tries to use a sidestore:// link without SideStore already installed, it will crash, so some documentation may be helpful.
+For more info, see [URL Schema](/docs/advanced/url-schema). It is often helpful to create the link to your AltSource in this format, then put it into a link shortener such as ```tinyurl.com```. However, if a user tries to use a sidestore:// link without SideStore already installed, it will crash, so some documentation may be helpful.
 
 ## That's it!