docs: Fix readme broken image

Fix readme broken markdown example image

README.md

@@ -33,7 +33,7 @@ Currently, the extension supports `.http` and `.md` files, feel free to add any
 
 To be able to see the navigation left menu in markdown files, you just need to open the file and click in the plugin icon in the left bar.
 
-![Markdown file support](image.png)
+![Markdown file support](images/readme-markdown-eg.png)
 
 
 ### HTTP Files
@@ -67,4 +67,4 @@ In this example, the navigation tree will display "Section" and "Section 2" as p
 
 ## License
 
-This extension is licensed under the MIT License.
+This extension is licensed under the MIT License.