Button tutorial fix

https://doc.qt.io/qtdesignstudio/quick-buttons.html

Creating Button step by step. or it should be, however this tutorial misses all the needed information to create a functional button you can click. Most of the information in the page is not needed for the button anyway.

Also, after the title, there should be line that tells what is the end goal of the tutorial, so user don't have to read all the text and notice that it is not what they were looking for.