🔥Feature: add function to check if request came from localhost

[vecpeng]

Close #1629 .
Usages

func handleSomething(c *fiber.Ctx) error {
	// Print true when request came from localhost
	fmt.Println(c.IsFromLocal())
	return nil
}

[ReneWerner87]

thanks for the feature

please provide a part in our docs(@vecpeng )
https://github.com/gofiber/docs/blob/master/api/ctx.md

[vecpeng]

OK, I open a pull request here. gofiber/docs#218