doc: update rule usage guide

Author: phhien203

README.md

@@ -6,13 +6,19 @@ This is a repository containing custom ESLint rules for Angular projects
 
 ## Rules included
 
-`destroy-service-provider`: When using `DestroyService` to automatically unsubscribe from an observable, this service MUST be provided in Component/Directive class providers in order for the Service to work properly. This rule ensures the DestroyService is always provided in the `providers` array of the Component or Directive.
+- `destroy-service-provider`: When using `DestroyService` to automatically unsubscribe from an observable, this service MUST be provided in Component/Directive class providers in order for the Service to work properly. This rule ensures the DestroyService is always provided in the `providers` array of the Component or Directive.
 
 ## Usage
 
-### `destroy-service-provider`
+### Install the package
 
-Edit your eslint config file as follow
+```bash
+npm install --save-dev eslint-plugin-ngx-eslint
+```
+
+### Config rule `destroy-service-provider`
+
+Edit your `.eslintrc` config file as follow
 
 ```json
 {
@@ -23,6 +29,22 @@ Edit your eslint config file as follow
 }
 ```
 
+If your destroy service class name is different than `DestroyService`, the configuration would be like this
+
+```json
+{
+  "plugins": ["ngx-eslint"],
+  "rules": {
+    "ngx-eslint/destroy-service-provider": [
+      "error",
+      {
+        "destroyServiceName": "MyDestroyService"
+      }
+    ]
+  }
+}
+```
+
 ## LICENSE
 
 MIT