Update Musical Keyboard Documentation

[pikurasa]

I think we ought to update https://github.com/sugarlabs/musicblocks/tree/master/guide#411-music-keyboard

Also, is it "Music Keyboard" or "musical keyboard"? We should try to be consistent.

[PriyalsantoshJain]

I tried to update the above link but couldn't found required portion in https://github.com/sugarlabs/musicblocks/blob/master/guide/index.html after line 1069.

[walterbender]

The index.html file is generated from the .md file. It is woefully out of date. But we can regenerate it after the other updates.

[ricknjacky]

@walterbender I presume this has been resolved as part of issue #2591 and PRs pertaining to it, right?

[walterbender]

We may want to tweak it, but yes, this is resolved.