Update references/joins.mdx (#295)

Co-authored-by: mintlify[bot] <109931778+mintlify[bot]@users.noreply.github.com>

Author: mintlify[bot]

references/joins.mdx

@@ -401,6 +401,8 @@ models:
               sql: IF(${subscriptions.plan} = 'premium', ${user_id}, NULL)
 ```
 
+If you get the following error: `Model "TABLE" has a metric reference: ${TABLE.DIMENSION} which matches no metric` - you likely have a mismatch in metric category. Read more about metric categories [here](/references/metrics#metric-categories).
+
 <Warning>
   **Every joined field that you reference in a YAML file adds a dependency that you'll have to include in all future references to that model.**