Adds example that uses coroutines.

coroutine.cpp

@@ -0,0 +1,51 @@
+#include <boost/asio.hpp>
+
+#include "aedis.hpp"
+
+namespace net = aedis::net;
+using tcp = net::ip::tcp;
+using tcp_socket = net::use_awaitable_t<>::as_default_on_t<tcp::socket>;
+
+namespace this_coro = net::this_coro;
+
+using namespace net;
+using namespace aedis;
+
+awaitable<void> example()
+{
+   auto executor = co_await this_coro::executor;
+
+   tcp::resolver resolver_(executor);
+   auto const res = resolver_.resolve("127.0.0.1", "6379");
+
+   tcp_socket socket {executor};
+   co_await async_connect(socket, res);
+
+   auto cmd = ping()
+            + role()
+            + multi()
+            + set("age", {"39"})
+            + incr("age")
+            + get("age")
+            + expire("Age", 10)
+            + publish("channel", "message")
+            + exec()
+	    + quit()
+	    ;
+
+   co_await async_write(socket, buffer(cmd));
+
+   resp::buffer buffer;
+   for (;;) {
+      co_await resp::async_read(socket, &buffer);
+      resp::print(buffer.res);
+      buffer.res.clear();
+   }
+}
+
+int main()
+{
+   io_context ioc {1};
+   co_spawn(ioc, example(), detached);
+   ioc.run();
+}