Fixed typo for "mogrify" in index.html (#482)

index.html

@@ -2856,7 +2856,7 @@ If the error message includes other parts of the command, such as a flag, that i
         <p>Creates thumbnails for all files in a folder and saves them in that folder.</p>
         <p><code>mogrify -resize 80x80 -format jpg -quality 75 -path thumbs *.jpg</code></p>
         <dl>
-          <dt>montage</dt><dd>starts the command</dd>
+          <dt>mogrify</dt><dd>starts the command</dd>
           <dt>-resize 80x80</dt><dd>resizes copies of original images to 80x80 pixels</dd>
           <dt>-format jpg</dt><dd>reformats original images to jpg</dd>
           <dt>-quality 75</dt><dd>sets quality to 75 (out of 100), adding light compression to smaller files</dd>