Update README.md

README.md

@@ -6,13 +6,13 @@ A "die roll string" is a string that contains an expression that defines operati
 Examples
 ========
 
-* 1d6
+* "1d6"
  * Roll a single six-sided die. This expression evaluates to the result of the roll.
-* 1d20+5
+* "1d20+5"
  * Roll a single twenty-sided die; add 5 to the rolled number and return.
-* 4d6
+* "4d6"
  * Roll four six-sided dice; add up the individual rolls and return the total.
-* 5d6-2d20+5
+* "5d6-2d20+5"
  * Roll five six-sided dice and add up the rolls; roll two twenty-sided dice, add up the two rolls, and subtract from the previous total; add 5 to the result; return.
 
 What Are Dice?