Just avoids a redirect

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: Duncanma

docs/develop/ruby/activities/standalone-activities-quickstart.mdx

@@ -34,7 +34,7 @@ Activity directly from your Temporal Client.
 :::note
 
 This documentation uses source code from the
-[standalone_activity](https://github.com/temporalio/samples-ruby/blob/main/standalone_activity)
+[standalone_activity](https://github.com/temporalio/samples-ruby/tree/main/standalone_activity)
 sample.
 
 :::