fix: add missing alt methods and semigroup

Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>

either/apply.go

@@ -24,6 +24,7 @@ func ApplySemigroup[E, A any](s S.Semigroup[A]) S.Semigroup[Either[E, A]] {
 	return S.ApplySemigroup(MonadMap[E, A, func(A) A], MonadAp[A, E, A], s)
 }
 
+// ApplicativeMonoid returns a [Monoid] that concatenates [Either] instances via their applicative
 func ApplicativeMonoid[E, A any](m M.Monoid[A]) M.Monoid[Either[E, A]] {
 	return M.ApplicativeMonoid(Of[E, A], MonadMap[E, A, func(A) A], MonadAp[A, E, A], m)
 }