README.md: Use condᵉ instead of eitherᵍ/bothᵍ

condᵉ is so much nicer, and much more kanren-like.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
adderall.dsl: Minor stylistic fix

Use the canonical name of bothᵍ, not the alias in the implementation of
allᵍ.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>