More improvements in the examples.

examples/basic2.cpp

@@ -1,4 +1,5 @@
 /* Copyright (c) 2019 - 2021 Marcelo Zimbres Silva (mzimbres at gmail dot com)
+/// \example basic1.cpp
  *
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -57,3 +58,5 @@ int main()
    co_spawn(ioc, ping(), net::detached);
    ioc.run();
 }
+
+/// \example basic2.cpp