title: Remove 'command not found' error discord.py
body: <p>In a discord.py rewrite bot, if someone types the bots prefix and then any text after it, if the text is not found as a command you will get </p>
  
  <pre><code>Ignoring exception in command None:
  discord.ext.commands.errors.CommandNotFound: Command "sd" is not found
  </code></pre>
  
  <p>Is there anyway to stop the bot from logging this?</p>