Suggestion: Health-check example

[mzimbres]

Async could provide a health check as an example since it is simple enough to implement and useful in general. Constraints

• Ping the server periodically (can be a http endpoint).
• Use only one timer.
• The timer should not be cancelled.
• On expiration the timer should exit with success.

The interface could look like

co_await health_check(connection, std::chrono::seconds{1});

[klemens-morgenstern]

I am not sure I get what this supposed to do.