feat Add numofdigits subject

subjects/numofdigits/README.md

@@ -0,0 +1,44 @@
+## numofdigits
+
+### Instructions
+
+Write a function that returns number of digits in a nonnegative integer n.
+- if you enter a negative input return 0.
+
+### Expected function
+
+```go
+func Numofdigits(int n) int {
+
+}
+```
+
+### Usage
+
+```go
+package main
+
+import (
+	"github.com/01-edu/z01"
+	"piscine"
+)
+
+func main() {
+	z01.PrintRune(piscine.Numofdigits(3))
+	z01.PrintRune(piscine.Numofdigits(245))
+	z01.PrintRune(piscine.Numofdigits(-1))
+	z01.PrintRune(piscine.Numofdigits(885))
+	z01.PrintRune(piscine.Numofdigits(8574))
+	z01.PrintRune('\n')
+}
+```
+
+And its output :
+
+```console
+$ go run .
+1$
+3$
+0$
+3$
+4$