Is `chord` supposed to be optional or not?

[bannmann]

DESIGN.md makes it sound like the chord feature is optional (emphasis mine):

3.5 Chord matcher (optional, chord feature)

Yet README.md and Cargo.toml say the opposite (emphasis mine):

Chord Matching

The default chord feature adds a state machine (…)

[features]
default = ["chord"]

Which one should it be?

Personally, I would prefer it being optional. I won't use it in my code base, but I also think being optional would fit better with keytap's overall "no frills, no superfluous stuff" attitude.

However, I have no trouble just disabling the default features.