refactor(tic_tac_toe): all results are now lowercase

subjects/tic_tac_toe/README.md

@@ -4,7 +4,7 @@
 
 You must create some functions for a tic-tac-toe checker.
 
-Create a function named `tic_tac_toe`, which receives a tic-tac-toe table. It should return the appropriate string: `"player O won"`, `"player X won"` or `"Tie"`.
+Create a function named `tic_tac_toe`, which receives a tic-tac-toe table. It should return the appropriate string: `"player O won"`, `"player X won"` or `"tie"`.
 
 
 Also create the following functions, which each accept a player and a table. These functions should return `true` if the player has completed one of the diagonals, rows or columns:
@@ -64,7 +64,7 @@ And its output
 
 ```console
 $ cargo run
-"Tie"
+"tie"
 "player O won"
 "player X won"
 $