Add update instructions to install section and FAQ

- Install section tip now mentions re-running the same command to update
- New FAQ entry: "How do I update to the latest version?" covering
  npx skills, Claude Code plugin marketplace, and manual ZIP
- Notes that .impeccable.md is preserved across updates

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/index.html

@@ -299,7 +299,7 @@
         </div>
       </div>
 
-      <p class="download-tip" data-reveal>Once installed, keep the <a href="/cheatsheet">command cheatsheet</a> handy for quick reference.</p>
+      <p class="download-tip" data-reveal>Once installed, keep the <a href="/cheatsheet">command cheatsheet</a> handy for quick reference. To update, just run the same install command again — it overwrites with the latest version.</p>
     </section>
 
     <!-- 5. CHANGELOG -->
@@ -392,6 +392,19 @@
           </div>
         </details>
 
+        <details class="faq-item">
+          <summary class="faq-question">How do I update to the latest version?</summary>
+          <div class="faq-answer">
+            <p>Run the same command you used to install — it overwrites your files with the latest version:</p>
+            <ul>
+              <li><strong>All tools:</strong> <code>npx skills add pbakaus/impeccable</code></li>
+              <li><strong>Claude Code plugin:</strong> Open <code>/plugin</code>, go to the Discover tab, and update from there</li>
+              <li><strong>Manual ZIP:</strong> Download the latest ZIP from above and extract to your project root, overwriting existing files</li>
+            </ul>
+            <p>Your <code>.impeccable.md</code> design context file (created by <code>/teach-impeccable</code>) is never overwritten — your project context is preserved across updates.</p>
+          </div>
+        </details>
+
         <details class="faq-item">
           <summary class="faq-question">Commands or skills aren't appearing. What do I do?</summary>
           <div class="faq-answer">