feat(piscine-go): Add README.md for new go exercise descendappendrange

subjects/descendappendrange/README.md

@@ -0,0 +1,46 @@
+## descendappendrange
+
+### Instructions
+
+- Write a function that takes an `int` max and an `int` min as parameters. The function should return a slice of `int`s with all the values between the max and min.
+
+- The `Max`must be included, and min must be excluded.
+
+- If max is inferior than or equal to min, a `nil` slice is returned.
+
+- `make`is not allowed for this exercise
+
+### Expected function
+
+```go
+func DescendAppendRange(max, min int) []int {
+
+}
+```
+
+### Usage
+
+Here is a possible program to test your function:
+
+```go
+package main
+
+import (
+	"fmt"
+	"piscine"
+)
+
+func main() {
+	fmt.Println(piscine.DescendAppendRange(10, 5))
+	fmt.Println(piscine.DescendAppendRange(5, 10))
+}
+```
+
+And its output:
+
+```console
+$ go run .
+[10 9 8 7 6]
+[]
+$
+```