Use singular for directory names

example/hello/benches/snuggle_speed.rs

@@ -0,0 +1,9 @@
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use hello::snuggle;
+
+pub fn snuggle_benchmark(c: &mut Criterion) {
+    c.bench_function("snuggle 2", |b| b.iter(|| snuggle(black_box(2))));
+}
+
+criterion_group!(benches, snuggle_benchmark);
+criterion_main!(benches);