Updated readme

Readme.md

@@ -14,6 +14,26 @@ npm i gatsby-plugin-appsync
 
 ## Usage
 
+Create an environment variable file which holds config params inside the root of your project
+
+**.env.[stage-name]**
+
+e.g
+
+.env.development
+
+```yaml
+AWS_REGION=eu-west-2
+COGNITO_USER_POOL_ID=
+COGNITO_APP_CLIENT_ID=
+COGNITO_IDENTITY_POOL_ID=
+AUTH_TYPE=API_KEY # AWS_IAM, AMAZON_COGNITO_USER_POOLS, OPENID_CONNECT
+AUTH_API_KEY=12345 # if using API_KEY
+GRAPHQL_ENDPOINT=<AppSync GraphQL Endpoint>
+S3_BUCKET_URL=<S3 Bucket URL>  # Required for s3 uploads using complexObjectsCredentials
+S3_MAX_ATTACHMENT_SIZE=2000000
+```
+
 Add plugin in gatsby-config.js
 
 **Usage with react hooks but no offline support yet**
@@ -27,7 +47,7 @@ module.exports = {
 };
 ```
 
-Same usage applies as using latest version of React Apollo Version 3+, which supports hooks.
+Same usage applies as using the latest version of React Apollo ( v 3+), with hooks.
 
 e.g