chore: update readme and upgrade guide

CHANGELOG.md

@@ -1,6 +1,10 @@
 # Change Log
 All notable changes to this project will be documented in this file.
 
+[2024-10-04] Version 4.0.0-rc.1
+---------------------------
+Release Candidate Preparation
+
 [2024-08-26] Version 3.16.0
 ---------------------------
 **Library - Chore**

README.md

@@ -89,6 +89,49 @@ source ./sendgrid.env
 
 The following is the minimum needed code to send an email with the [/mail/send Helper](helpers/mail) ([here](examples/helpers/mail/example.go#L32) is a full example):
 
+### Using Autogenerated Code
+```go
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/sendgrid/sendgrid-go"
+	MailV3 "github.com/sendgrid/sendgrid-go/rest/api/v3/mail"
+	"net/http"
+	"os"
+)
+
+func main() {
+	client := sendgrid.NewRestClientWithParams(sendgrid.ClientParams{
+		ApiKey: os.Getenv("SENDGRID_API_KEY"),
+	})
+	name := "John Doe"
+	subject := "Sending with Twilio SendGrid is Fun"
+	mailTo := &MailV3.MailTo{Email: "[email protected]"}
+	to := []MailV3.MailTo{*mailTo}
+	sendMailRequest := MailV3.SendMailRequest{
+		From:             MailV3.MailFrom{Name: &name, Email: VERIFIED_EMAIL},
+		ReplyTo:          mailTo,
+		Subject:          &subject,
+		Personalizations: []MailV3.SendMailRequestPersonalizationsInner{{To: to}},
+		Content:          &[]MailV3.SendMailRequestContentInner{{Type: "text/plain", Value: "Abc"}},
+	}
+	sendMailParam := &MailV3.SendMailParam{SendMailRequest: &sendMailRequest}
+	resp, err := client.MailV3.SendMail(sendMailParam)
+	if err != nil {
+		fmt.Println("Error sending mail: " + err.Error())
+	} else {
+		response, _ := json.Marshal(resp)
+		var ps http.Response
+		json.Unmarshal(response, &ps)
+		fmt.Println(ps.StatusCode)
+		fmt.Println(ps.Body)
+		fmt.Println(ps.Header)
+	}
+}
+```
+
 ### With Mail Helper Class
 
 ```go

UPGRADE.md

@@ -0,0 +1,11 @@
+# Upgrade Guide
+
+_`MAJOR` version bumps will have upgrade notes posted here._
+
+[2024-10-04] 3.x.x to 4.x.x-rc.x
+--------------------------------
+### Overview
+
+#### Sendgrid Go Helper Library's version 4.0.0-rc.x is now available.
+
+Behind the scenes Go Helper is now auto-generated via OpenAPI with this release. This enables us to rapidly add new features and enhance consistency across versions and languages.

base_interface.go

@@ -15,7 +15,7 @@ import (
 
 // Version is this client library's current version
 const (
-	Version        = "3.16.0"
+	Version        = "4.0.0-rc.1"
 	rateLimitRetry = 5
 	rateLimitSleep = 1100
 )