#456 Documentation: FLAC detailed spec fails to mention that difference channels have an extra bit

[Timothy Miller]

It seems like an oversight that the FLAC detailed spec (https://xiph.org/flac/format.html) fails to mention that difference/side channels have an extra bit per sample.

In retrospect, perhaps it may seem obvious that the diffence between two n-bit channels must use n+1 bits. However, the fact that what is an otherwise brilliantly-written spec failed to mention this caused me quite a lot of headaches.