Doc: add few deployment steps

Author: meanii

README.md

@@ -1,4 +1,19 @@
 # aws-lambda-hls-enc
 > Go-powered AWS Lambda tool for swift and efficient HLS file encryption, empowering direct encryption of HLS files within Lambda. Boosts flexibility and scalability for managing media streaming workflows on AWS.
 
+## Deployment
+
+1. Create AWS Lambda function with API Gateway
+   - Runtime: `Amazon Linux 2`
+   - Architecture: `arm64`
+
+
+2. Now, you need to configure a few environment variables.
+
+| Name                          | Value Type      | Description                          |
+|-------------------------------| ----------------| -------------------------------------|
+| CLOUDFRONT_ACCESS_KEY_ID      | String          | Cloudfront Public KeyID              |
+| CLOUDFRONT_ORIGIN             | String          | Cloudfront CDN Domain                |
+| CLOUDFRONT_PRIVATE_KEY_BASE64 | String          | Cloudfront Generated Private Key     |
+| EXPIRE_TIME                   | String          | Signature URL Expiry Time, e.g. (2h) |