Added stopwatch example to README.md

README.md

@@ -169,6 +169,21 @@ spdlog::flush_every(std::chrono::seconds(3));
 
 ```
 
+---
+#### Stopwatch
+```c++
+// Stopwatch support for spdlog  (using std::chrono::high_resolution_clock).
+// Displays elapsed seconds since construction as double.
+#include "spdlog/stopwatch.h"
+void stopwatch_example()
+{
+    spdlog::stopwatch sw;    
+    spdlog::debug("Elapsed {}", sw);
+    spdlog::debug("Elapsed {:.3}", sw);       
+}
+
+```
+
 ---
 #### Log binary data in hex
 ```c++