docs: add example show_notification

examples/show_notification.rs

@@ -0,0 +1,23 @@
+use libnotify_rs::{
+    functions::{init, uninit},
+    notification::Notification,
+};
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    init("I love coffee");
+    let mut notify = Notification::new(
+        "Remember to drink coffe!",
+        "Coffee is very important for your mental health!",
+        None,
+    )?;
+
+    notify.set_timeout(libnotify_rs::notification::Timeout::Custom(1000 * 10)); // 10 secs
+    notify.set_urgency(libnotify_rs::notification::Urgency::Critical); // coffee is very important
+    notify.set_category("Coffee")?;
+
+    notify.show()?;
+
+    uninit();
+
+    Ok(())
+}