Add screenshot to the readme

[Reinmar]

Cause it should be here :)

[mateuszzagorski]

I was wondering if we shouldn't go a little bit further with this - possibly creating a visual table comparison between 'old' Github and Github Writer.

What I mean by that is, for example:

	GitHub Default	GitHub Writer
Tables	| OrderDate | Region | Rep | |---|---|---| | 9/1/14 | Central | Smith | | 6/17/15 | Central | Kivell |
Mermaid	```mermaid flowchart TB A --> B B --> C ```

Highlighting the new functionalities could be an option as well of course.

Although we would have to find a solution for two problems:

1.  I believe there should be some kind of additional textual explanation of what is going on regarding the mermaid for example. Adding a column is a possibility, but because of that the images would shrink significantly. 

2. The other thing is to add proper screenshots, if I'm not missing anything, we would be forced to add additional logic to detect which theme is the person viewing the readme using ( light or dark ), and based on that alter the displayed image. 

   // This part is pretty straightforward in Markdown:

![GitHub-Mark-Light](https://user-images.githubusercontent.com/11699569/197994809-d381e1c2-b1a4-4481-9de0-8301f67fbfc8.png#gh-dark-mode-only)
![GitHub-Mark-Dark](https://user-images.githubusercontent.com/11699569/197999885-cedab563-3fce-4966-bfcd-52dd541a2f05.png#gh-light-mode-only)