How to document refactoring on legacy code

I am working on legacy code(VS 2012, c#.net). I am writing unit testing by using MS fakes. To document every thing I have done, I started to create test case with VS Test Manager for every unit test. I also refactored some parts of code. Has any one any idea how I can document my refactoring activities?

I am trying to document every changes I have made to report to manager. All of my refactoring changes are separate from main project and they will be merged to main one after finishing documentation.

Thanks,