Readme instruction on docker . Fix

### Information about bug

http://erpnext.localhost:8000/app
**port change from 8000 to 8080**

your container after bootup shows 8080 port 

Not creating a pull request, as its a minor error.

### Module

other

### Version

Erpnext v14.85.2

### Installation method

None

### Relevant log output / Stack trace / Full Error Message.

```shell

```