Document the 'header' event in the README.
Document the 'header' event in the README.

PlayNetwork/node-lame,mcanthony/node-lame,shine-on/node-lame,dag10/node-lame,dag10/node-lame,EQ4/node-lame,dag10/node-lame,TooTallNate/node-lame,TooTallNate/node-lame,mcanthony/node-lame,EQ4/node-lame,shine-on/node-lame,PlayNetwork/node-lame,shine-on/node-lame,EQ4/node-lame,TooTallNate/node-lame,PlayNetwork/node-lame,mcanthony/node-lame