www: set autocomplete="off" for the wifi psk field

esp32/www/config.html

@@ -18,7 +18,7 @@
 	</label>
 	<label class="wifi-psk">
 	  <span>Network password (PSK):</span>
-	  <input class="mono" type="password" name="wifi.psk" />
+	  <input class="mono" type="password" autocomplete="off" name="wifi.psk" />
 	  <button type="button" class="show" onclick="showpwd()"><span class="show">Show</span><span class="hide">Hide</span></button>
 	</label>
       </fieldset>