Add cookies example.

examples/cookies/config.ru

@@ -0,0 +1,17 @@
+#!/usr/bin/env falcon --verbose serve -c
+# frozen_string_literal: true
+
+require 'rack/request'
+
+KEY = 'my cookie'
+
+run do |env|
+	request = Rack::Request.new(env)
+	puts "My Cookie: #{request.cookies[KEY]}"
+	puts "All Cookies: #{request.cookies}"
+
+	headers = {}
+	Rack::Utils.set_cookie_header!(headers, KEY, 'bar')
+
+	[200, headers, ["Hello World!"]]
+end