docs: Explain what to do when slice is empty or there are no odd elements as per review

docs: Remove piscine imports and refactor as per review

subjects/oddlength/README.md

@@ -2,7 +2,7 @@
 
 ### Instructions
 
-Write a function that receives a slice of strings and returns a new slice with the strings in which the length is odd.
+Write a function that receives a slice of strings and returns a new slice with the strings in which the length is odd. When the slice is empty or there are no odd strings return an empty slice.
 
 ### Expected function
 
@@ -19,14 +19,10 @@ Here is a possible program to test your function:
 ```go
 package main
 
-import (
+import "fmt"
-    "piscine"
-    "fmt"
-)
 
 func main() {
-    l := piscine.Oddlength(["Hi", "Hola", "Ola", "Ciao", "Salut", "Hallo"])
+    fmt.Println(Oddlength(["Hi", "Hola", "Ola", "Ciao", "Salut", "Hallo"]))
-    fmt.Println(l)
 }
 ```