remove duplicate section

Author: thepriefy

README.md

@@ -61,24 +61,6 @@ Install smtpapi-nodejs and its dependencies:
 npm install
 ```
 
-## Setup Environment Variables
-
-### Initial Setup
-
-```bash
-cp .env_sample .env
-```
-
-### Environment Variable
-
-Update the development environment with your [SENDGRID_API_KEY](https://app.sendgrid.com/settings/api_keys), for example:
-
-```bash
-echo "export SENDGRID_API_KEY='YOUR_API_KEY'" > sendgrid.env
-echo "sendgrid.env" >> .gitignore
-source ./sendgrid.env
-```
-
 ## Dependencies
 
 - Please see [package.json](https://github.com/sendgrid/smtpapi-nodejs/blob/master/package.json)