examples/: Add sleep.cpp

rt/examples/sleep.cpp

+#include <typon/typon.hpp>
+#include <typon/logger.hpp>
+
+#include <chrono>
+
+using namespace typon;
+
+Task<void> sleep(int t) {
+  LOG("sleep(%d)", t);
+  co_await io::sleep(std::chrono::seconds(t));
+  LOG("sleep(%d) >>> woke up", t);
+}
+
+Join<void> parallel() {
+  for (int t = 0; t < 10; t++) {
+    co_await fork(sleep(t / 2 + 1));
+  }
+}
+
+Root root() {
+  co_await parallel();
+}
+
+int main() {
+  root().call();
+  puts("done");
+  return 0;
+}