Make opi more visible to new users

Could we introduce it in `openSUSE Welcome > Readme` page. For example, add a new section like this:

>**Quick way**
> You can quickly install these extra software with `opi`

into this:

![image](https://user-images.githubusercontent.com/11857205/154827945-b0ed64ba-85d2-4a83-b36e-7fdcdb1e52ca.png)
