feat: add humantime-demo

__time/humantime-demo/src/main.rs

@@ -0,0 +1,11 @@
+use std::time::{Duration, SystemTime};
+
+fn main() {
+    let formatted = humantime::format_duration(
+        SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap()
+    );
+    println!("{}", formatted);
+
+    let formatted = humantime::format_duration(Duration::from_millis(1000000));
+    println!("{}", formatted);
+}