docs(fromto): instructions upgrade

subjects/fromto/README.md

@@ -0,0 +1,47 @@
+## fromto
+
+### Instructions
+
+Write a function that takes two `integers` and returns a `string` showing the range of numbers from the first to the second.
+
+- The numbers must be separated by a comma and a space.
+- If any of the arguments is bigger than 99 or less than 0, the function returns `Invalid` followed by a newline `\n`.
+- Add a `0` at the beginning of any number if it is less than 10.
+- Add a new line `\n` at the end of the `string`.
+
+### Expected function
+
+```go
+func FromTo(from int, to int) string {
+
+}
+```
+
+### Usage
+
+Here is a possible program to test your function:
+
+```go
+package main
+
+import (
+	"fmt"
+	"piscine"
+)
+
+func main() {
+	fmt.Print(piscine.FromTo(1, 10))
+	fmt.Print(piscine.FromTo(10, 1))
+	fmt.Print(piscine.FromTo(10, 10))
+	fmt.Print(piscine.FromTo(100, 10))
+}
+```
+And its output:
+
+```console
+$ go run . | cat -e
+01, 02, 03, 04, 05, 06, 07, 08, 09, 10$
+10, 09, 08, 07, 06, 05, 04, 03, 02, 01$
+10$
+Invalid$
+```