Add Cookbook S01-S22 (draft)

docs-src/pages/en/cookbook/s19-graceful-shutdown.md

@@ -0,0 +1,57 @@
+---
+title: "S19. Shut Down Gracefully"
+order: 38
+status: "draft"
+---
+
+To stop the server, call `Server::stop()`. It's safe to call even while requests are in flight, so you can wire it to SIGINT or SIGTERM for a graceful shutdown.
+
+## Basic usage
+
+```cpp
+httplib::Server svr;
+
+svr.Get("/", [](const auto &, auto &res) { res.set_content("ok", "text/plain"); });
+
+std::thread t([&] { svr.listen("0.0.0.0", 8080); });
+
+// wait for input on the main thread, or whatever
+std::cin.get();
+
+svr.stop();
+t.join();
+```
+
+`listen()` blocks, so the typical pattern is: run the server on a background thread and call `stop()` from the main thread. After `stop()`, `listen()` returns and you can `join()`.
+
+## Shut down on a signal
+
+Here's how to stop the server on SIGINT (Ctrl+C) or SIGTERM.
+
+```cpp
+#include <csignal>
+
+httplib::Server svr;
+
+// global so the signal handler can reach it
+httplib::Server *g_svr = nullptr;
+
+int main() {
+  svr.Get("/", [](const auto &, auto &res) { res.set_content("ok", "text/plain"); });
+
+  g_svr = &svr;
+  std::signal(SIGINT,  [](int) { if (g_svr) g_svr->stop(); });
+  std::signal(SIGTERM, [](int) { if (g_svr) g_svr->stop(); });
+
+  svr.listen("0.0.0.0", 8080);
+  std::cout << "server stopped" << std::endl;
+}
+```
+
+`stop()` is thread-safe and signal-safe — you can call it from a signal handler. Even when `listen()` is running on the main thread, the signal pulls it out cleanly.
+
+## What happens to in-flight requests
+
+When you call `stop()`, new connections are refused, but requests already being processed are **allowed to finish**. Once all workers drain, `listen()` returns. That's what makes it graceful.
+
+> **Warning:** There's a wait between calling `stop()` and `listen()` returning — it's the time in-flight requests take to finish. To enforce a timeout, you'll need to add your own shutdown timer in application code.