readme for new exercice of quest05 alphacount

subjects/alphacount.en.md

@@ -0,0 +1,42 @@
+## alphacount
+
+### Instructions
+
+Write a function that counts only the letters of a `string` and that returns that count.
+White spaces or any other characters should not be counted.
+
+### Expected function
+
+```go
+func AlphaCount(str string) int {
+
+}
+```
+
+### Usage
+
+Here is a possible [program](TODO-LINK) to test your function :
+
+```go
+package main
+
+import (
+	"fmt"
+	piscine ".."
+)
+
+func main() {
+	str := "Hello 78 World!    4455 /"
+	nb := piscine.AlphaCount(str)
+	fmt.Println(nb)
+}
+```
+
+And its output :
+
+```console
+student@ubuntu:~/piscine-go/test$ go build
+student@ubuntu:~/piscine-go/test$ ./test
+10
+student@ubuntu:~/piscine-go/test$
+```