chore: update GitHub branch references to use HEAD

CONTRIBUTING.md

@@ -51,7 +51,7 @@ We welcome direct contributions to the smtpapi-nodejs code base. Thank you!
 
 - Node.js version 0.10, 0.12 or 4
 - The SendGrid Service, starting at the [free level](https://sendgrid.com/free?source=smtpapi-nodejs)
-- Please see [package.json](https://github.com/sendgrid/smtpapi-nodejs/blob/master/package.json)
+- Please see [package.json](package.json)
 
 ##### Initial setup: #####
 
@@ -76,7 +76,7 @@ source ./sendgrid.env
 
 ##### Execute: #####
 
-See the [examples folder](https://github.com/sendgrid/smtpapi-nodejs/tree/master/examples) to get started quickly.
+See the [examples folder](examples) to get started quickly.
 
 To run the example (after updating the settings and the emails):
 
@@ -104,9 +104,9 @@ Source code.
 
 All PRs require passing tests before the PR will be reviewed.
 
-All test files are in the [`test`](https://github.com/sendgrid/smtpapi-nodejs/tree/master/test) directory.
+All test files are in the [`test`](test) directory.
 
-For the purposes of contributing to this repo, please update the [`main.js`](https://github.com/sendgrid/smtpapi-nodejs/blob/master/test/main.js) file with unit tests as you modify the code.
+For the purposes of contributing to this repo, please update the [`main.js`](test/main.js) file with unit tests as you modify the code.
 
 To run the tests:
 
@@ -124,7 +124,7 @@ Generally, we follow the style guidelines as suggested by the official language.
 Please run your code through:
 
 - [ESLint](http://eslint.org/) with the standard style guide.
-- [esdoc](https://github.com/sendgrid/smtpapi-nodejs/blob/master/USAGE.md) to check the documentation coverage of your added code.
+- [esdoc](USAGE.md) to check the documentation coverage of your added code.
 
 ## Creating a Pull Request<a name="creating-a-pull-request"></a>
 
@@ -167,7 +167,7 @@ Please run your code through:
 5. Locally merge (or rebase) the upstream development branch into your topic branch:
 
    ```bash
-   git pull [--rebase] upstream master
+   git pull [--rebase] upstream main
    ```
 
 6. Push your topic branch up to your fork:
@@ -177,7 +177,7 @@ Please run your code through:
    ```
 
 7. [Open a Pull Request](https://help.github.com/articles/using-pull-requests/)
-    with a clear title and description against the `master` branch. All tests must be passing before we will review the PR.
+    with a clear title and description against the `main` branch. All tests must be passing before we will review the PR.
 
 <a name="code-reviews"></a>
 ## Code Reviews

README.md

@@ -1,6 +1,6 @@
-![SendGrid Logo](https://uiux.s3.amazonaws.com/2016-logos/email-logo%402x.png)
+![SendGrid Logo](twilio_sendgrid_logo.png)
 
-[![BuildStatus](https://travis-ci.org/sendgrid/smtpapi-nodejs.png?branch=master)](https://travis-ci.org/sendgrid/smtpapi-nodejs)
+[![BuildStatus](https://travis-ci.org/sendgrid/smtpapi-nodejs.png?branch=main)](https://travis-ci.org/sendgrid/smtpapi-nodejs)
 [![npm](https://img.shields.io/npm/v/smtpapi.svg)](https://www.npmjs.com/package/smtpapi)
 [![Email Notifications Badge](https://dx.sendgrid.com/badge/nodejs)](https://dx.sendgrid.com/newsletter/nodejs)
 [![MIT licensed](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE.md)
@@ -12,7 +12,7 @@
 # Announcements
 **The default branch name for this repository has been changed to `main` as of 07/27/2020.**
 
-All updates to this module are documented in our [CHANGELOG](https://github.com/sendgrid/smtpapi-nodejs/blob/master/CHANGELOG.md).
+All updates to this module are documented in our [CHANGELOG](CHANGELOG.md).
 
 # Table of Contents
 - [Installation](#installation)
@@ -52,7 +52,7 @@ npm install smtpapi
 
 ## Dependencies
 
-- Please see [package.json](https://github.com/sendgrid/smtpapi-nodejs/blob/master/package.json)
+- Please see [package.json](package.json)
 
 <a name="quick-start"></a>
 # Quick Start
@@ -76,14 +76,14 @@ If you are interested in the future direction of this project, please take a loo
 <a name="contribute"></a>
 # How to Contribute
 
-We encourage contribution to our projects, please see our [CONTRIBUTING](https://github.com/sendgrid/smtpapi-nodejs/blob/master/CONTRIBUTING.md) guide for details.
+We encourage contribution to our projects, please see our [CONTRIBUTING](CONTRIBUTING.md) guide for details.
 
 Quick links:
 
-- [Feature Request](https://github.com/sendgrid/smtpapi-nodejs/blob/master/CONTRIBUTING.md#feature-request)
-- [Bug Reports](https://github.com/sendgrid/smtpapi-nodejs/blob/master/CONTRIBUTING.md#submit-a-bug-report)
-- [Improvements to the Codebase](https://github.com/sendgrid/smtpapi-nodejs/blob/master/CONTRIBUTING.md#improvements-to-the-codebase)
-- [Review Pull Requests](https://github.com/sendgrid/smtpapi-nodejs/blob/master/CONTRIBUTING.md#code-reviews)
+- [Feature Request](CONTRIBUTING.md#feature-request)
+- [Bug Reports](CONTRIBUTING.md#submit-a-bug-report)
+- [Improvements to the Codebase](CONTRIBUTING.md#improvements-to-the-codebase)
+- [Review Pull Requests](CONTRIBUTING.md#code-reviews)
 
 <a name="about"></a>
 # About

TROUBLESHOOTING.md

@@ -12,7 +12,7 @@ If you can't find a solution below, please open an [issue](https://github.com/se
 <a name="versions"></a>
 ## Versions
 
-We follow the MAJOR.MINOR.PATCH versioning scheme as described by [SemVer.org](http://semver.org). Therefore, we recommend that you always pin (or vendor) the particular version you are working with to your code and never auto-update to the latest version. Especially when there is a MAJOR point release, since that is guaranteed to be a breaking change. Changes are documented in the [CHANGELOG](https://github.com/sendgrid/smtpapi-nodejs/blob/master/CHANGELOG.md) section.
+We follow the MAJOR.MINOR.PATCH versioning scheme as described by [SemVer.org](http://semver.org). Therefore, we recommend that you always pin (or vendor) the particular version you are working with to your code and never auto-update to the latest version. Especially when there is a MAJOR point release, since that is guaranteed to be a breaking change. Changes are documented in the [CHANGELOG](CHANGELOG.md) section.
 
 <a name="package-manager"></a>
 ## Using the Package Manager

USAGE.md

@@ -12,4 +12,4 @@ You will find a coverage.json file in the docs directory. This will contain info
 
 # More information 
 - [SendGrid Docs](https://sendgrid.com/docs/API_Reference/SMTP_API/index.html)
-- [Example Code](https://github.com/sendgrid/smtpapi-nodejs/blob/master/examples)
+- [Example Code](examples)