Add struct and method examples

Includes new struct definitions and methods for Celsius, Persona, and
Rectangulo. Also adds examples of their usage in the main function.

README.md

@@ -9,3 +9,6 @@ https://www.youtube.com/watch?v=ID9NZ88JeOE
 
 //intermedio.go
 1. (00:38:46) continue
+2. (00:56:07) struct
+
+//avanzado.go

intermedio.go

@@ -2,6 +2,25 @@ package main
 
 import "fmt"
 
+type Celsius float64
+
+func (c Celsius) toFahrenheit() float64 {
+	return float64(c * 9 / 5 * 32)
+}
+
+type Persona struct {
+	Nombre string
+	Edad   int
+}
+
+type Rectangulo struct {
+	Width, Height float64
+}
+
+func (r Rectangulo) Area() float64 {
+	return r.Width * r.Height
+}
+
 func main() {
 	fmt.Println("Hola mundo")
 
@@ -28,7 +47,7 @@ func main() {
 
 	for i := 0; i < 5; i++ {
 		if i%2 == 0 {
-			fmt.Println(i, " es par")
+			fmt.Println(i, "es par")
 			continue
 		}
 		fmt.Println(i)
@@ -37,10 +56,50 @@ func main() {
 	for i := 1; i <= 3; i++ {
 		for j := 1; j <= 3; j++ {
 			if j == 2 {
-				continue
+				continue // solo afecta al bucle interno
 			}
-			fmt.Println("i=", i, "j=", j)
+			// fmt.Println("i=", i, "j=", j)
+			fmt.Printf("i=%d j=%d\n", i, j)
 		}
 	}
 
+	nums := []int{1, 2, 3, 4, 5}
+	for i, num := range nums {
+		fmt.Printf("index=%d valor=%d\n", i, num)
+	}
+
+	m := map[string]int{"uno": 1, "dos": 2, "tres": 3}
+	for k, v := range m {
+		fmt.Printf("key=%s valor=%d\n", k, v)
+	}
+
+	x = 2
+	switch x {
+	case 1:
+		fmt.Println("1")
+	case 2:
+		fmt.Println("2")
+		fallthrough
+	case 3:
+		fmt.Println("3")
+	default:
+		fmt.Println("default")
+	}
+
+	// defer fmt.Println("salida") // deferido al final de la ejecución
+	fmt.Println("salida2")
+
+	for i := 0; i < 5; i++ {
+		// defer fmt.Println(i) // deferido al final de la ejecución
+	}
+	fmt.Println("Fin del loop")
+
+	temp := Celsius(100)
+	fmt.Println(temp.toFahrenheit())
+
+	p := Persona{Nombre: "Juan", Edad: 30}
+	fmt.Println(p.Nombre)
+
+	r := Rectangulo{Width: 10, Height: 20}
+	fmt.Println(r.Area())
 }