youtube-dl: clearer description of mp3 example

pages/common/youtube-dl.md

@@ -6,7 +6,7 @@
 
 `youtube-dl {{https://www.youtube.com/watch?v=oHg5SJYRHA0}}`
 
-- Download the audio from a video as an MP3:
+- Download the audio from a video and convert it to an MP3:
 
 `youtube-dl -x --audio-format {{mp3}} {{url}}`