Clarifying variables/secrets distinction

app.py

@@ -818,7 +818,7 @@ CSS_STYLES = """
     }
     .gradio-container h1::after {
         grid-row: 3;
-        content: "Authentication is optional but Image/Video Generation require a `HF_READ_TOKEN` in env variables. They are hidden otherwise.";
+        content: "Authentication is optional but Image/Video Generation require a `HF_READ_TOKEN` in env secrets. They are hidden otherwise.";
         display: block;
         font-size: 1rem;
         font-weight: 400;