DEV-3189 add(docs):add subject of secondHalf ex

subjects/secondslice/README.md

@@ -0,0 +1,38 @@
+## Second-Slice
+
+### Instructions
+
+Write a function that receives a slice with integers and returns a new one with the last half of the values. If the length is odd, round it down.
+
+### Expected function
+
+```go
+func SecondSlice(slice []int) []int {
+
+}
+```
+
+### Usage
+
+Here is a possible program to test your function :
+
+```go
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	fmt.Println(SecondHalf([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}))
+    fmt.Println(SecondHalf([]int{1, 2, 3}))
+}
+```
+
+And its output :
+
+```console
+$ go run .
+[5,6,7,8,9,10]
+[2,3]
+```