Fixed openzeppelin fundamentals link

Author: 7i7o

lessons/projects/3.mdx

@@ -122,7 +122,7 @@ npm install @openzeppelin/contracts
 <ContentCallout emoji='💡' size='md' variant='info'>
 Open Zeppelin developed a lot of standard contracts that are super powerful,
 widely used and fully tested and audited. Read more about them
-[here](/lessons/open_zeppelin).
+[here](/lessons/fundamentals/open_zeppelin).
 </ContentCallout>
 
 ### Let’s start coding!