docs: update study intro text to reflect 3 conditions

static/index.html

@@ -281,9 +281,9 @@
             <h2>Help us prove FlowRead works!</h2>
             <p style="max-width: 600px; margin: 0 auto 2rem; color: #4b5563;">
                 We are testing if LLM-guided saliency highlighting improves reading speed, comprehension, and retention. 
-                You will be shown two short texts (one plain, one FlowRead-enhanced) and asked a few quick questions.
+                You will be shown three short texts (one plain, one FlowRead bolding, one FlowRead gradient) and asked a few quick questions.
             </p>
-            <button id="start-study-btn" style="font-size: 1.25rem; padding: 1rem 2rem;">Start the 2-Minute Study</button>
+            <button id="start-study-btn" style="font-size: 1.25rem; padding: 1rem 2rem;">Start the 3-Minute Study</button>
         </div>
 
         <!-- Step 1.5: Loading -->