Improve explanation after successful submit.

src/main.cpp

@@ -64,6 +64,9 @@ int main()
         cout << "Created pull request: <"
              << "https://schlomp.space/FediBlock/data/pulls/"
              << gitea::get_last_pr_number() << ">.\r\n";
+        cout << "Your entry needs to be approved before it appears on the "
+                "website. You can subscribe to notifications or add comments "
+                "at the URL above.\r\n";
 
         files::remove_tmpdir();
     }