docs: Moved usage and enviorment variables to USAGE.md (#86)

* Moved the example and example link along with the environment variables to the USAGE.md
* Changed the Table of Contents to reference the new USAGE.md

Author: rareinator

README.md

@@ -15,7 +15,7 @@ If you are looking for the SendGrid API client library, please see [this repo](h
 * [Announcements](#announcements)
 * [Installation](#installation)
 * [Quick Start](#quick-start)
-* [Usage](#usage)
+* [Usage](./USAGE.md)
 * [Roadmap](#roadmap)
 * [How to Contribute](#contribute)
 * [About](#about)
@@ -116,37 +116,6 @@ try {
 }
 ```
 
-<a name="usage"></a>
-# Usage
-
-- [Example Code](https://github.com/sendgrid/java-http-client/tree/master/examples)
-- [Library Usage Documentation](USAGE.md)
-
-
-The example uses SendGrid, you can get your free account [here](https://sendgrid.com/free?source=java-http-client).
-
-First, update your environment with your [SENDGRID_API_KEY](https://app.sendgrid.com/settings/api_keys).
-
-```bash
-echo "export SENDGRID_API_KEY='YOUR_API_KEY'" > sendgrid.env
-echo "sendgrid.env" >> .gitignore
-source ./sendgrid.env
-```
-
-```bash
-mvn package
-cd examples
-javac -classpath {path_to}/sendgrid-java-http-client-4.0.0-jar.jar:. Example.java && java -classpath {path_to}/sendgrid-java-http-client-4.0.0-jar.jar:. Example
-```
-
-## Environment Variables
-
-You can do the following to create a .env file:
-
-```cp .env_example .env```
-
-Then, just add your API Key into your .env file.
-
 <a name="roadmap"></a>
 # Roadmap
 

USAGE.md

@@ -16,4 +16,12 @@ source ./sendgrid.env
 mvn package
 cd examples
 javac -classpath {path_to}/sendgrid-java-http-client-4.0.0-jar.jar:. Example.java && java -classpath {path_to}/sendgrid-java-http-client-4.0.0-jar.jar:. Example
-```
+```
+
+## Environment Variables 
+
+You can do the following to create a .env file:
+
+```cp .env_example .env```
+
+Then, just add your API Key into your .env file.