Update README.md

Adding validator in grammar file.

1 files changed, 7 insertions, 0 deletions

diff --git a/README.md b/README.md
index b085529..c1e8dc4 100644
--- a/README.md
+++ b/README.md
@@ -6,8 +6,15 @@ Rolisteam Dice Parser
 The grammar is something like this:
 
 Command =: Expression
+
 Expression =: number | number Dice | ScalarOperator Expression
+
 Dice =: DiceOperator Number(faces)
+
 DiceOperator =: D
+
 ScalarOperator =: [x,-,*,x,/]
+
 number =: [0-9]+
+
+Validator =: number | [operator number] | [ number - number ]