Update Readme.md

Readme.md

@@ -13,3 +13,15 @@ Run `./target/release/homomorphic_game_of_life` (or `./target/release/homomorphi
 ## What does it do exactly?
 
 This is a very simple implementation of Conway's [Game of Life](https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life) using periodic boundary conditions, with a twist: the board is encrypted using a fully homomorphic encryption scheme ([TFHE](https://eprint.iacr.org/2018/421.pdf)) and all calculations are performed in encrypted space. In principle, calculations can thus be done by a thread or server which has no access to the state of the board. 
+
+## Config and initial states
+
+The file `Config.csv` is read at startup and defines the following parameters (first line of the file):
+
+* the wait time between two updates in microseconds (no effect if much smaller than the time needed to compute one update),
+* the pixel size,
+* the board dimensions (if no initial state is provided; these two values are currently ignored),
+* the background colour in rgb format,
+* the foreground color in rgb format. 
+
+The file `initial_state.csv` defines the initial state.