docs: add basic code samples

README.md

@@ -125,6 +125,35 @@ const nightwatch = @import("nightwatch");
 
 You now have programmatic access to the tracking engine.
 
+### Example
+
+```zig
+const nightwatch = @import("nightwatch");
+const std = @import("std");
+
+const H = struct {
+    handler: nightwatch.Default.Handler,
+
+    const vtable = nightwatch.Default.Handler.VTable{ .change = change, .rename = rename };
+
+    fn change(_: *nightwatch.Default.Handler, path: []const u8, event: nightwatch.EventType, _: nightwatch.ObjectType) error{HandlerFailed}!void {
+        std.debug.print("{s}  {s}\n", .{ @tagName(event), path });
+    }
+
+    fn rename(_: *nightwatch.Default.Handler, src: []const u8, dst: []const u8, _: nightwatch.ObjectType) error{HandlerFailed}!void {
+        std.debug.print("rename  {s}  ->  {s}\n", .{ src, dst });
+    }
+};
+
+var h = H{ .handler = .{ .vtable = &H.vtable } };
+var watcher = try nightwatch.Default.init(allocator, &h.handler);
+defer watcher.deinit();
+try watcher.watch("/path/to/dir");
+// watcher delivers events on a background thread until deinit()
+```
+
+See the [`examples/`](examples/) directory for complete, buildable programs.
+
 ---
 
 # CLI Usage