Fixing music doc issues

docs/reference/music.md

@@ -6,7 +6,6 @@ Generation of music tones through pin ``P0``.
 music.playTone(0, 0);
 music.ringTone(0);
 music.rest(0);
-music.noteFrequency(Note.C);
 music.beat(BeatFraction.Whole);
 music.tempo();
 music.changeTempoBy(20);
@@ -15,4 +14,4 @@ music.setTempo(120);
 
 ### See Also
 
-[playTone](/reference/music/play-tone), [ringTone](/reference/music/ring-tone), [rest](/reference/music/rest), [noteFrequency](/reference/music/note-frequency), [beat](/reference/music/beat), [tempo](/reference/music/tempo), [changeTempoBy](/reference/music/change-tempo), [setTempo](/reference/music/set-tempo)
+[playTone](/reference/music/play-tone), [ringTone](/reference/music/ring-tone), [rest](/reference/music/rest), [beat](/reference/music/beat), [tempo](/reference/music/tempo), [changeTempoBy](/reference/music/change-tempo-by), [setTempo](/reference/music/set-tempo)

docs/reference/music/beat.md

@@ -0,0 +1,30 @@
+# Beat
+
+Returns the duration of a beat in milli-seconds
+
+## Simulator
+
+This function only works on the micro:bit and in some browsers.
+
+```sig
+music.beat(BeatFraction.Whole)
+```
+
+### Parameters
+
+* ``BeatFraction`` means fraction of a beat (BeatFraction.Whole, BeatFraction.Sixteenth etc) 
+
+### Returns
+
+* a [number](/reference/types/number) that means the amount of milli-seconds a beat fraction represents.
+
+
+## Example
+
+```blocks
+music.playTone(Note.C, music.beat(BeatFraction.Quarter))
+```
+
+### See also
+
+[play tone](/reference/music/play-tone), [ring tone](/reference/music/ring-tone), [rest](/reference/music/rest), [set tempo](/reference/music/set-tempo), [change tempo by](/reference/music/change-tempo-by)

docs/reference/toc.md

@@ -22,7 +22,7 @@ change
 
 change-score-by
 
-change-tempo
+change-tempo-by
 
 change-var
 

libs/core/music.ts

@@ -211,7 +211,7 @@ namespace music {
      * Change the tempo by the specified amount
      * @param bpm The change in beats per minute to the tempo, eg: 20
      */
-    //% help=music/change-tempo weight=39
+    //% help=music/change-tempo-by weight=39
     //% blockId=device_change_tempo block="change tempo by (bpm)|%value" blockGap=8
     export function changeTempoBy(bpm: number): void {
         init();