feat: add example for builder

examples/builder.rs

@@ -0,0 +1,23 @@
+use libnotify_rs::{builder::NotificationBuilder, context::LibnotifyContext};
+
+/// Builder is recommended way to interact with libnotify notifications
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let ctx = LibnotifyContext::new("Coffee addicted reminder")?; // builder requires context
+
+    let notification_builder = NotificationBuilder::new(
+        "Remember about your coffee!",
+        "Only idiots forget about coffee!",
+        None,
+        &ctx,
+    )?
+    .set_urgency(libnotify_rs::notification::Urgency::Critical)
+    .set_timeout(libnotify_rs::notification::Timeout::Never)
+    .set_category("Coffee")?;
+
+    notification_builder.show()?;
+
+    // you don't need to uninitialize libnotify, cause context already does that!
+
+    Ok(())
+}