Add a link to cget

Author: pfultz2

README.md

@@ -848,6 +848,7 @@ array expressions, inspired by NumPy syntax. [BSD 3-clause] [website](http://qua
 * [clib](https://github.com/clibs/clib) - Package manager for the C programming language. [MIT]
 * [CMake](https://cmake.org/) - Cross-platform free and open-source software for managing the build process of software using a compiler-independent method. [BSD]
 * [C++ Archive Network](https://cppan.org/) - Cross-platform C++ Dependency Manager with a lot of packages available.
+* [Cget](https://github.com/pfultz2/cget) - Cmake package retrieval. [Boost] [website](http://cget.readthedocs.io)
 * [Conan](https://conan.io/) - C/C++ Package Manager, open sourced. [MIT]
 * [CPM](https://github.com/iauns/cpm) - A C++ Package Manager based on CMake and Git.
 * [FASTBuild](http://www.fastbuild.org/docs/home.html) - High performance, open-source build system supporting highly scalable compilation, caching and network distribution.