website/_content/doc: fix package name mentioned in go getting-started tutorial

Author: Taz03

_content/doc/tutorial/getting-started.html

@@ -217,7 +217,7 @@ <h2 id="call">Call code in an external package</h2>
       </li>
       <li>
         Locate and click the <code>rsc.io/quote</code> package in search results
-        (if you see <code>rsc.io/quote/v3</code>, ignore it for now).
+        (if you see <code>rsc.io/quote/v4</code>, ignore it for now).
       </li>
       <li>
         In the <strong>Documentation</strong> section, under <strong>Index</strong>, note the