Update README.md

README.md

@@ -29,6 +29,7 @@ Very fast, header only, C++ logging library. [![Build Status](https://travis-ci.
 * Very fast - performance is the primary goal (see [benchmarks](#benchmarks) below).
 * Headers only, just copy and use.
 * Feature rich [call style](#usage-example) using the excellent [fmt](https://github.com/fmtlib/fmt) library.
+* Optional printf syntax support.
 * Extremely fast asynchronous mode (optional) - using lockfree queues and other tricks to reach millions of calls/sec.
 * [Custom](https://github.com/gabime/spdlog/wiki/3.-Custom-formatting) formatting.
 * Conditional Logging