Docs Env Support (#507)

* added env support docs in quickstart guide

* added bulid script info

* Update quickstart.md

docs/indexer/quickstart/quickstart.md

@@ -117,3 +117,42 @@ For example, to create the [Ethereum Gravatar indexer](./quickstart_chains/ether
 Once completed, you will have a scaffold project structure from your chosen ABI `functions`/`events`.
 
 You can read more about this feature in [Project Scaffolding](../build/introduction.md#evm-project-scaffolding)
+
+## ENV Support
+
+SubQuery provides support for environment variables to configure your project dynamically. This enables flexibility in managing different configurations for development, testing, and production environments.
+
+To utilize environment variable support:
+
+The .env files are automatically created when you initialize a project using the CLI. You can modify these files to adjust configurations according to your requirements.
+
+```shell
+# Example .env
+ENDPOINT=https://polygon-rpc.com
+CHAIN_ID=204
+```
+
+In your .env files, *CHAIN_ID* and provided *ENDPOINT* of your project are already added you can configure these variables to match your blockchain network settings. Additionally, you can keep sensitive information such as *CONTRACT_ADDRESS* from project.ts in your .env files for added security.
+
+Multiple ENDPOINT can be added in .env file using comma separated.
+
+```shell
+ENDPOINT=https://polygon-rpc.com,https://polygon.llamarpc.com
+```
+
+The package.json file includes build scripts that allow you to build with either production (`.env`) or development (`.env.develop`).
+
+```json
+"scripts": {
+    "build": "subql codegen && subql build", // default is production
+    "build:develop": "NODE_ENV=develop subql codegen && NODE_ENV=develop subql build"
+}
+```
+Use `build` script to generate artifacts using the default production .env settings.
+Use `build:develop` script to generate artifacts using the development .env.develop settings.
+
+Using environment variables and .env files provides a convenient way to manage project configurations and keep sensitive information secure.
+
+Note: Ensure that .env files are included in your project's .gitignore to prevent them from being committed to version control and exposing sensitive information.
+
+This documentation provides comprehensive guidance on utilizing environment variable support in SubQuery projects for better configurability and security.