add geolocalize button

src/babillard_page.eml.html

@@ -14,6 +14,7 @@ let f ~board request =
 <a href=<%s url %>>[New Thread]</a>
 % end;
 <div id="map"></div>
+<button onclick="geolocalize()">Geolocalize me</button>
       </div>
       <div class="col-md-6">
 <div id="thread_preview_div"></div>