docs: Add information for rules in eslint-config-turbo README.

packages/eslint-config-turbo/README.md

@@ -1,4 +1,4 @@
-# `eslint-config-turbo`
+# `eslint-plugin-turbo`
 
 Ease configuration for Turborepo
 
@@ -10,18 +10,44 @@ Ease configuration for Turborepo
 npm install eslint --save-dev
 ```
 
-2. Next, install `eslint-config-turbo`:
+2. Next, install `eslint-plugin-turbo`:
 
 ```sh
-npm install eslint-config-turbo --save-dev
+npm install eslint-plugin-turbo --save-dev
 ```
 
 ## Usage
 
-Add `turbo` to the extends section of your eslint configuration file. You can omit the `eslint-config-` prefix:
+Add `turbo` to the plugins section of your `.eslintrc` configuration file. You can omit the `eslint-plugin-` prefix:
 
 ```json
 {
-  "extends": ["turbo"]
+  "plugins": ["turbo"]
+}
+```
+
+Then configure the rules you want to use under the rules section.
+
+```json
+{
+  "rules": {
+    "turbo/no-undeclared-env-vars": "error"
+  }
+}
+```
+
+### Example
+
+```json
+{
+  "plugins": ["turbo"],
+  "rules": {
+    "turbo/no-undeclared-env-vars": [
+      "error",
+      {
+        "allowList": ["^ENV_[A-Z]+$"]
+      }
+    ]
+  }
 }
 ```