some more docs

README.md

@@ -1,10 +1,15 @@
 # sudoku
-Compile time sudoku
+Compile time sudoku. Just an example for compile time evaluation, used for demonstration purposes for our 
+local c++ user group and for my colleguages at work. Tested with clang only (as my older gcc was not able
+to compile the constexpr stuff...)
 
 ## classic
 This is a quick shot implementation of a sudoku solver, used at starting point for the compile time variant. 
 
 ## constexpr
 This is the compile time variant. Works for me with clang 3.6, needs C++14 (constexpr using "if" and loops). 
 
+## qt
+This is just a graphical frontend to demonstrate the problem and visualize how backtracking works. 
+
 See also [my blog](http://www.valpo.de/?p=190)