update README

Author: lasconic

README.md

@@ -5,6 +5,7 @@ This is a plugin for MuseScore 1.2 to add harmonica tablature notation below the
  * Diatonic D - [Reference](http://musescore.org/sites/musescore.org/files/Lee%20Oskar%20Diatonic%20D.jpg)
  * Diatonic G - [Reference](http://musescore.org/sites/musescore.org/files/Lee%20Oskar%20%20Diatonic%20G.jpg)
  * Diatonic Bb - [Reference](http://musescore.org/sites/musescore.org/files/Lee%20Oskar%20Diatonic%20Bb.jpg)
+ * Chromatic C, 12 holes - [Reference](http://musescore.org/sites/musescore.org/files/12%20Hole%20Chromatic%20slide%20Harmonica.txt)
 
 
 If you want to have your harmonica added to the it, please contact me, or better, do a pull request.
@@ -16,6 +17,7 @@ If you want to have your harmonica added to the it, please contact me, or better
 * '  = halfstep bend
 * "  = whole step bend
 * "' = 3 halfsteps bend
+* "<" = slide
 
 Bends, over blow, over draw may be supported if it's the only way to play the note. 
 If there are two holes for one note, a choice has been made (draw)