Add a visual helptext in the description of class to provide a visual part in the element where the class will be placed

Problem/Motivation

In order to have the project easier should be good have one example in the block class field exaplining the exactly place on eleemtn were this one will be displayed

Steps to reproduce

Proposed resolution

Add the new screenshot, update the formAlter and include this example form description in the field

Remaining tasks

User interface changes

API changes

Data model changes