title: Project Reactor: Sum two Mono<Integer> without blocking
body: <p>Suppose that we have:</p>
  <p><code>Mono&lt;Integer&gt; int1 = Mono.just(1)</code> and <code>Mono&lt;Integer&gt; int2 = Mono.just(10)</code>. I would like get the sum of these two integer without blocking.</p>
  <p>In the blocking way I would do this:
  <code>Mono&lt;Integer&gt; result = Mono.just(int1.block() + int2.block())</code></p>
  <p>Thanks in advance!</p>