docs(countalpha): fix subject

- fix indentation
- fix grammar

subjects/countalpha/README.md

@@ -2,34 +2,33 @@
 
 ### Instructions
 
-Write a function `CounAlpha` that takes a string in parameter and returns the number of alphabetic characters in the string.
+Write a function `CountAlpha()` that takes a string as an argument and returns the number of alphabetic characters in the string.
 
 ### Expected functions
 
 ```go
 func CountAlpha(s string) int {
+
 }
 ```
 
 ### Usage
 
-Here is a program to test your function.
+Here is a possible program to test your function:
 
 ```go
 package main
 
-import (
+import "fmt"
-    "fmt"
-)
 
 func main() {
-    fmt.Println(CountAlpha("Hello world"))
+	fmt.Println(CountAlpha("Hello world"))
-    fmt.Println(CountAlpha("H e l l o"))
+	fmt.Println(CountAlpha("H e l l o"))
-    fmt.Println(CountAlpha("H1e2l3l4o"))
+	fmt.Println(CountAlpha("H1e2l3l4o"))
 }
 ```
 
-And its output :
+And its output:
 
 ```console
 $ go run .