Finish introduction

Architecture.md

@@ -35,3 +35,18 @@ flowchart TD
     solve --> print3
     print3 --> stop
 ```
+
+The program can be split into multiple parts. The above diagram showing the
+general flow, but putting the `solve puzzle` part into a black box. This
+subroutine contains the actual algorithm, and will be analysed later. The other
+functions a more trivial, but nonetheless necessary. We need:
+
+- A routine that prints text on the terminal
+- We need a routine, that can grab the parameters a user passed to the command
+  line, and read the command line parameters. since ITS does not have a built-in
+  mechanism for this, we need to write our own.
+- We need to be able to open the file, that was passed to us, and open it, as
+  well as reading the data from it.
+- We need a data structure to store the playing field in.
+- We need a routine, that clears the screen and shows the current state of the
+  playing grid on the screen.