Rename embedding to struct embedding to be separated from //go:embed directive (#424)

Signed-off-by: peterzhu1992 <peterzhu1992@gmail.com>

examples/struct-embedding/struct-embedding.go

@@ -0,0 +1,62 @@
+// Go supports _embedding_ of structs and interfaces
+// to express a more seamless _composition_ of types.
+// This is not to be confused with `//go:embed` which is
+// a go directive introduced in Go version 1.16+ to embed
+// files and folders into the application binary.
+
+package main
+
+import "fmt"
+
+type base struct {
+	num int
+}
+
+func (b base) describe() string {
+	return fmt.Sprintf("base with num=%v", b.num)
+}
+
+// A `container` _embeds_ a `base`. An embedding looks
+// like a field without a name.
+type container struct {
+	base
+	str string
+}
+
+func main() {
+
+	// When creating structs with literals, we have to
+	// initialize the embedding explicitly; here the
+	// embedded type serves as the field name.
+	co := container{
+		base: base{
+			num: 1,
+		},
+		str: "some name",
+	}
+
+	// We can access the base's fields directly on `co`,
+	// e.g. `co.num`.
+	fmt.Printf("co={num: %v, str: %v}\n", co.num, co.str)
+
+	// Alternatively, we can spell out the full path using
+	// the embedded type name.
+	fmt.Println("also num:", co.base.num)
+
+	// Since `container` embeds `base`, the methods of
+	// `base` also become methods of a `container`. Here
+	// we invoke a method that was embedded from `base`
+	// directly on `co`.
+	fmt.Println("describe:", co.describe())
+
+	type describer interface {
+		describe() string
+	}
+
+	// Embedding structs with methods may be used to bestow
+	// interface implementations onto other structs. Here
+	// we see that a `container` now implements the
+	// `describer` interface because it embeds `base`.
+	var d describer = co
+	fmt.Println("describer:", d.describe())
+}

examples/struct-embedding/struct-embedding.hash

@@ -0,0 +1,2 @@
+a246237126303fb110186ac2598bca15d36e8366
+TqMui3hJuX7

examples/struct-embedding/struct-embedding.sh

@@ -0,0 +1,5 @@
+$ go run struct-embedding.go
+co={num: 1, str: some name}
+also num: 1
+describe: base with num=1
+describer: base with num=1