Add speed limit icons to WebUI Speed options

src/webui/www/private/preferences_content.html

@@ -291,6 +291,9 @@
         <legend>QBT_TR(Global Rate Limits)QBT_TR[CONTEXT=OptionsDialog]</legend>
         <table>
             <tr>
+                <td rowspan="2">
+                    <img alt="QBT_TR(Alternative speed limits)QBT_TR[CONTEXT=MainWindow]" src="images/slow_off.png">
+                </td>
                 <td><label for="up_limit_value">QBT_TR(Upload:)QBT_TR[CONTEXT=OptionsDialog]</label></td>
                 <td><input type="number" id="up_limit_value" style="width: 4em;" min="0" />&nbsp;&nbsp;QBT_TR(KiB/s)QBT_TR[CONTEXT=OptionsDialog]</td>
             </tr>
@@ -306,6 +309,9 @@
         <legend>QBT_TR(Alternative Rate Limits)QBT_TR[CONTEXT=OptionsDialog]</legend>
         <table>
             <tr>
+                <td rowspan="2">
+                    <img alt="QBT_TR(Alternative speed limits)QBT_TR[CONTEXT=MainWindow]" src="images/slow.png">
+                </td>
                 <td><label for="alt_up_limit_value">QBT_TR(Upload:)QBT_TR[CONTEXT=OptionsDialog]</label></td>
                 <td><input type="number" id="alt_up_limit_value" style="width: 4em;" min="0" />&nbsp;&nbsp;QBT_TR(KiB/s)QBT_TR[CONTEXT=OptionsDialog]</td>
             </tr>