Update README

Author: AXeL-dev

README.md

@@ -39,14 +39,21 @@ npm install --save ngx-diff2html
   export class AppModule {}
 ```
 
-**2**. Add the following line to `polyfills.ts`:
+**2**. Import diff2html css in `styles.css`:
+
+```diff
+  /* You can add global styles to this file, and also import other style files */
++ @import "~diff2html/dist/diff2html.min.css";
+```
+
+**3**. Add the following line to `polyfills.ts`:
 
 ```diff
   // Add global to window, assigning the value of window itself.
 + (window as any).global = window;
 ```
 
-**3**. Start using the component:
+**4**. Start using the component:
 
 ```html
 <ngx-diff2html
@@ -67,7 +74,7 @@ npm install --save ngx-diff2html
 | -------------------- | ----------------- | ------------------------------------ | --------------------------
 | left                 | string            | Yes                                  | First text to be compared
 | right                | string            | Yes                                  | Second text to be compared
-| filename             | string            | Optional, default: ` ` (white space) | Can be used to display a filename in the top of diff results. **Cannot be null or empty**
+| filename             | string            | Optional, default: `` (empty)        | Can be used to display a filename at the top of diff results.
 | format               | `DiffFormat`      | Optional, default: `side-by-side`    | Possible values:<br> - `side-by-side`<br> - `line-by-line`
 | style                | `DiffStyle`       | Optional, default: `word`            | Possible values:<br> - `word`<br> - `char`
 

projects/ngx-diff2html/README.md

@@ -39,14 +39,21 @@ npm install --save ngx-diff2html
   export class AppModule {}
 ```
 
-**2**. Add the following line to `polyfills.ts`:
+**2**. Import diff2html css in `styles.css`:
+
+```diff
+  /* You can add global styles to this file, and also import other style files */
++ @import "~diff2html/dist/diff2html.min.css";
+```
+
+**3**. Add the following line to `polyfills.ts`:
 
 ```diff
   // Add global to window, assigning the value of window itself.
 + (window as any).global = window;
 ```
 
-**3**. Start using the component:
+**4**. Start using the component:
 
 ```html
 <ngx-diff2html
@@ -67,7 +74,7 @@ npm install --save ngx-diff2html
 | -------------------- | ----------------- | ------------------------------------ | --------------------------
 | left                 | string            | Yes                                  | First text to be compared
 | right                | string            | Yes                                  | Second text to be compared
-| filename             | string            | Optional, default: ` ` (white space) | Can be used to display a filename in the top of diff results. **Cannot be null or empty**
+| filename             | string            | Optional, default: `` (empty)        | Can be used to display a filename at the top of diff results.
 | format               | `DiffFormat`      | Optional, default: `side-by-side`    | Possible values:<br> - `side-by-side`<br> - `line-by-line`
 | style                | `DiffStyle`       | Optional, default: `word`            | Possible values:<br> - `word`<br> - `char`