docs: add warning on where to place ngx-datatable styles

docs/en/UI/Angular/Migration-Guide-v3.md

@@ -237,9 +237,10 @@ Until v3, we had been using a custom component, `abp-table`, as the default tabl
 
 As of ABP v3, we have switched to a battle-tested, well-executed data grid: [ngx-datatable](https://github.com/swimlane/ngx-datatable). All ABP modules will come with ngx-datatable already implemented in them. `ThemeSharedModule` already exports `NgxDatatableModule`. So, if you install the package by running `yarn add @swimlane/ngx-datatable` in your terminal, it will be available for use in all modules of your app.
 
-For proper styling, you need to add the following in the styles section of your angular.json file:
+For proper styling, you need to add the following in the styles section of your angular.json file (above all others):
 
 ```json
+"styles": [
   {
     "input": "node_modules/@swimlane/ngx-datatable/index.css",
     "inject": true,
@@ -254,7 +255,9 @@ For proper styling, you need to add the following in the styles section of your
     "input": "node_modules/@swimlane/ngx-datatable/themes/material.css",
     "inject": true,
     "bundleName": "ngx-datatable-material"
-  }
+  },
+  // other styles
+]
 ```
 
 Since `abp-table` is not dropped yet, modules previously built by ABP v2.x will not suddenly lose all their tables. Yet, they will look and feel different from built-in ABP v3 modules. Therefore, you will probably want to convert the tables in those modules to ngx-datatable. In order to decrease the amount of work required to convert an abp-table into ngx-datatable, we have modified the [ListService](./List-Service.md) to work well with ngx-datatable and [introduced](https://volosoft.com/blog/attribute-directives-to-avoid-repetition-in-angular-templates) two new directives: `NgxDatatableListDirective` and `NgxDatatableDefaultDirective`.