docs: cache-bust the map screenshot URL past the Cloudflare edge

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

deploy/site/docs.html

@@ -209,7 +209,7 @@
           <p>An OpenStreetMap / OpenTopoMap view with your position and your contacts plotted as markers, plus link lines from you to each node. Tiles are fetched over Wi-Fi through the wadamesh proxy and cached to flash (or microSD), so areas you've viewed work offline.</p>
           <p>It also has a line-of-sight analyzer: pick a contact and it uses SRTM elevation to show whether terrain blocks the path.</p>
         </div>
-        <div class="shot"><div class="device"><img class="screen" src="docs-img/map.png" alt="Map"></div><div class="cap">Map</div></div>
+        <div class="shot"><div class="device"><img class="screen" src="docs-img/map.png?v=2" alt="Map"></div><div class="cap">Map</div></div>
       </div>
       <div class="prose">
         <h3>Bring your own tiles (offline maps)</h3>