Nitpick in the docs

[jefffohl]

@slurmulon - I was reading through the docs, and I think I found an error.

Based on this statement,

To adhere with music theory, numerical durations are strictly based on **common time** (`@meter = 4|4`).

I believe this line:

bach/docs/guide.md

Line 741 in ebac75a

This means that `1` always means four quarter notes, and only equates with a full measure when the number of beats in a measure is 4 (as in `4|4`, `3|4`, `5|4`, etc.).

Should read:

This means that `1` always means four quarter notes, and only equates with a full measure when the meter is `4|4`.

This is because 3|4 and 5|4 time don't have four quarter notes in a measure, but have 3 and 5 respectively.