Fix Copy/Paste issues in comments

[richardeigenmann]

Hi Martin

In my learning C++ course (in Zurich) we started experimenting with Mlpack. Since we like to use CMake I was looking for a FindMlpack.cmake module that Google helpfully found in your repo. It works very well, thank you.

I did notice some issues which look like copy/paste problems. I have taken the liberty to correct these and would like to offer the changes back to you in the form of this pull request. It would feel like I have done a good deed if you accept it.

Regards, Richard