Update README.md

Grammatical changes to the instructions.

subjects/issorted/README.md

@@ -2,9 +2,9 @@
 
 ### Instructions
 
-Write a function `IsSorted` that returns `true`, if the slice of `int` is sorted, and that returns `false` otherwise.
+Write a function `IsSorted` that returns `true`, if the slice of `int` is sorted, otherwise returns 'false'.
 
-The function passed in parameter returns a positive `int` if `a` (the first argument) is superior to `b` (the second argument), it returns `0` if they are equal and it returns a negative `int` otherwise.
+The function passed in the parameter returns a positive `int` if `a` (the first argument) is greater than to `b` (the second argument), it returns `0` if they are equal and it returns a negative `int` otherwise.
 
 To do your testing you have to write your own `f` function.
 
@@ -16,7 +16,7 @@ func IsSorted(f func(a, b int) int, a []int) bool {
 }
 ```
 
-### Usage
+### Testing
 
 Here is a possible program to test your function (without `f`):