Feature/example test (#24)

example docs

sliceUtil/merge_slice_example_test.go

@@ -0,0 +1,15 @@
+package sliceUtil
+
+import "fmt"
+
+func ExampleMergeSlice() {
+	slice1 := []int{1, 2, 3}
+	slice2 := []int{4, 5, 6}
+	slice3 := []int{7, 8, 9}
+	res := MergeSlice(slice1, slice2, slice3)
+
+	fmt.Printf("%+v", res)
+
+	// Output:
+	// [1 2 3 4 5 6 7 8 9]
+}