doc: add an example for create-bulk api (#650)

doc/md/crud.md

@@ -114,16 +114,29 @@ a8m, err := client.User.	// UserClient.
 	Save(ctx)				// Create and return.
 ```
 
-**SaveX** a user; Unlike **Save**, **SaveX** panics if an error occurs.
+**SaveX** a pet; Unlike **Save**, **SaveX** panics if an error occurs.
 
 ```go
 pedro := client.Pet.	// PetClient.
-	Create().			// User create builder.
+	Create().			// Pet create builder.
 	SetName("pedro").	// Set field value.
 	SetOwner(a8m).		// Set owner (unique edge).
 	SaveX(ctx)			// Create and return.
 ```
 
+## Create Many
+
+**Save** a bulk of pets.
+
+```go
+names := []string{"pedro", "xabi", "layla"}
+bulk := make([]*ent.PetCreate, len(names))
+for i, name := range names {
+    bulk[i] = client.Pet.Create().SetName(name).SetOwner(a8m)
+}
+pets, err := client.Pet.CreateBulk(bulk...).Save(ctx)
+```
+
 ## Update One
 
 Update an entity that was returned from the database.