Update README.md

Author: ArminGh02

README.md

@@ -27,6 +27,7 @@ The [benchmarks](benchmark/sort_benchmark.cpp) use **[Google Benchmark](https://
 
 ## How to Use
 
+This is a single-header library.  
 Just copy the **[sort.hpp](include/sorting_algorithms/sort.hpp)** header file to your project and include it!  
 All functions are in the ```alg::``` namespace.