docs ~ add arch example

examples/arch.rs

@@ -0,0 +1,21 @@
+// examples/arch.rs
+// * use `cargo run --example arch` to execute this example
+
+// spell-checker:ignore (API) nodename osname sysname
+
+use platform_info::*;
+
+fn main() {
+    let info = PlatformInfo::new().unwrap();
+    println!(
+        "{}",
+        match info.machine().to_os_string().into_string() {
+            Ok(s) => s,
+            Err(os_s) => {
+                let s = os_s.to_string_lossy();
+                eprintln!("machine = [{}]'{:?}' => '{}'", os_s.len(), os_s, s);
+                String::from(s)
+            }
+        }
+    );
+}