documented in readme my recent obstacles with macOS 10.12

README.md

@@ -19,7 +19,13 @@ Currently, the wrapper implements a demo method to run a recognition from the we
 
 ## Prerequisites
 
-Requires modern Node and NPM versions (tested with latest LTS release Node v6.*.*, npm 3.*.*, supposed to work with the newer versions as well). Also this module requires OpenCV (version 2, for example, 2.4.9.1) to be installed. First, you need to compile [this fork](https://github.com/OrKoN/darknet) of darknet with OpenCV support (optionally, with CUDA support):
+Requires:
+
+- Modern Node and NPM versions (tested with latest LTS release Node v6.*.*, npm 3.*.*, supposed to work with the newer versions as well)
+- OpenCV (version 2, for example, 2.4.9.1) to be installed on your system
+- If you are on a mac: macOS 10.12 Sierra or newer, Apple LLVM version 8.0.0 (xcode 8.2, check version with `clang -v`). For GPU support, Nvidia [CUDA Toolkit](https://developer.nvidia.com/cuda-downloads)
+
+First, you need to compile [this fork](https://github.com/OrKoN/darknet) of darknet with OpenCV support (optionally, with CUDA support):
 
 ```sh
 git clone https://github.com/OrKoN/darknet