Readme docs for running test are outdated

[Qix-]

The readme states you can run tests by running make but this is no longer the case; the library was switched to CMake in order to create a target and to honor the testing flags provided by CMake.

The readme should be updated to reflect this.

mkdir build && cd build
cmake .. -DBUILD_TESTING=ON -DCMAKE_BUILD_TYPE=Debug
cmake --build .
ctest

The above should be tested and, if correct, updated in the readme.

[Qix-]

Sure! PR welcome :)