docs(max-num): correct grammar

subjects/mobile-dev/max-num/README.md

@@ -1,28 +1,5 @@
-# Max Num
+## Max Num
 
 ### Instructions
 
-Write a function called `maxNum()` that takes three integers as arguments and returns the maximum number of the three.
-
-### Ternary operators
-
-One can do different things with ternary operators. It comes handy when one wants to do actions based on some condition.
-This operation also keeps less amount of code, and hopefully more readable.
-
-Typical form of the ternary operator is:
-
-```
-condition ? (value for true condition) : (value for false condition)
-```
-
-```dart
-bool four_greater_than_five = 4 > 5 ?  true : false;
-```
-
-- Note: The same could be achieved with simple if and else, but this approach reduces code length.
-
-### Usage
-
-```dart
-int maxNum(int first, int second, int third) {...}
-```
+Write a function named `maxNum`, which accepts `int` parameters, and returns the maximum number of the three.