Add simple example

examples/simple.rs

@@ -0,0 +1,19 @@
+use anyhow::Result;
+use macos_routing_table::{RouteEntry, RoutingTable};
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let rt = RoutingTable::load_from_netstat().await?;
+    let addr = "1.1.1.1".parse()?;
+
+    if let Some(RouteEntry {
+        net_if, gateway, ..
+    }) = rt.find_route_entry(addr)
+    {
+        println!("{addr:?} => {gateway} via {net_if}");
+    } else {
+        println!("No route to {addr:?}");
+    }
+
+    Ok(())
+}