DEV-3379-new-go-exercise-swap-last (#1368)

* DEV-3379 add subject swapLast

* rename the title

* docs(swaplast): fix subject

- upgrade instructions
- add missing import 'piscine'
- fix expected output
- fix white-spaces and indentation

* docs(swaplast): fix typo

---------

Co-authored-by: Tiago Collot <collot.tiago1@gmail.com>
Co-authored-by: Michele Sessa <mikysett@gmail.com>

subjects/swaplast/README.md

@@ -0,0 +1,44 @@
+## swaplast
+
+### Instructions
+
+ Write a function that takes as an argument a slice of integers and return another slice of integers with the last two elements swapped.
+
+> If the slice contains less than two elements return the same slice.
+
+### Expected function
+
+```go
+func SwapLast(slice []int) []int {
+
+}
+```
+
+### Usage
+
+Here is a possible program to test your function:
+
+```go
+package main
+
+import (
+	"fmt"
+	"piscine"
+)
+
+func main() {
+	fmt.Println(piscine.SwapLast([]int{1, 2, 3, 4}))
+	fmt.Println(piscine.SwapLast([]int{3, 4, 5}))
+	fmt.Println(piscine.SwapLast([]int{1}))
+}
+
+```
+
+And its output:
+
+```console
+$ go run .
+[1 2 4 3]
+[3 5 4]
+[1]
+```