fix closing tag

index.html

@@ -1123,7 +1123,7 @@ <h3>Flip audio phase shift</h3>
             <dt>ffmpeg</dt><dd>starts the command</dd>
             <dt>-i <i>input file</i></dt><dd>path, name and extension of the input file</dd>
             <dt>-af</dt><dd>specifies that the next section should be interpreted as an audio filter</dd>
-            <dt>pan=<dt><dd>tell the quoted text below to use the <a href="https://ffmpeg.org/ffmpeg-filters.html#pan-1" target="_blank">pan filter</a></dd>
+            <dt>pan=</dt><dd>tell the quoted text below to use the <a href="https://ffmpeg.org/ffmpeg-filters.html#pan-1" target="_blank">pan filter</a></dd>
             <dt>"stereo|c0=c0|c1=-1*c1"</dt><dd>maps the output's first channel (c0) to the input's first channel and the output's second channel (c1) to the inverse of the input's second channel</dd>
             <dt><i>output file</i></dt><dd>path, name and extension of the output file</dd>
           </dl>