Remove the wheel-up rewind

Holding the drop and the w key no longer spin it back and restart the
tune; the help and the first-start hint no longer mention it.

web/index.html

@@ -241,7 +241,6 @@
         <dt>double-tap</dt><dd>like</dd>
         <dt>swipe up / down</dt><dd>next / previous</dd>
         <dt>drag waveform</dt><dd>seek</dd>
-        <dt>hold the drop</dt><dd>wheel up: rewind the tune</dd>
       </dl>
       <dl class="pointer-only">
         <dt>click · space</dt><dd>play / pause</dd>
@@ -256,7 +255,6 @@
         <dt>z</dt><dd>zen: just the drop</dd>
         <dt>c</dt><dd>filters and settings</dd>
         <dt>h</dt><dd>history</dd>
-        <dt>w · hold drop</dt><dd>wheel up: rewind the tune</dd>
         <dt>0–9 · , .</dt><dd>jump to 0–90 % · seek 5 s</dd>
         <dt>m · + −</dt><dd>mute · volume</dd>
         <dt>?</dt><dd>this help</dd>