docs(iscapitalized): fix instructions

- fix exercise title
- upgrade instructions
- add missing import 'piscine'
- fix white-spaces and indentation

subjects/iscapitalized/README.md

@@ -0,0 +1,49 @@
+## iscapitalized
+
+### Instructions
+
+Write a function `IsCapitalized()` that takes a `string` as an argument and returns `true` if each word in the `string` begins with either an uppercase letter or a non-alphabetic character.
+
+- If any of the words begin with a lowercase letter return `false`.
+- If the `string` is empty return `false`.
+
+### Expected function
+
+```go
+func IsCapitalized(s string) bool {
+
+}
+```
+
+### Usage
+Here is a possible program to test your function:
+
+```go
+package main
+
+import (
+	"fmt"
+	"piscine"
+)
+
+func main() {
+	fmt.Println(piscine.IsCapitalized("Hello! How are you?"))
+	fmt.Println(piscine.IsCapitalized("Hello How Are You"))
+	fmt.Println(piscine.IsCapitalized("Whats 4this 100K?"))
+	fmt.Println(piscine.IsCapitalized("Whatsthis4"))
+	fmt.Println(piscine.IsCapitalized("!!!!Whatsthis4"))
+	fmt.Println(piscine.IsCapitalized(""))
+}
+```
+
+And its output:
+
+```console
+$ go run .
+false
+true
+true
+true
+true
+false
+```