Use case : Add a property to asset metadata.
By default, when you open an asset's properties you see something as below :
Now in order to add a custom property to it you need to do as below:
Let us suppose I need a text-box named "Test Title" in basic tab above title.
1. Go to aem start start.html.
2. Click on tools and then on side bar Assets.
3. Click on MetaData Schema.
4. Select the default one and edit it.
5. It will open Metadata Schema Form Editor as shown below:
6. Drag and drop any as per your requirement from right side bar, for now as I need a textfield so I will drop Single Line Text and will drop it above title in Basic tab.
7. Click on the field you have dropped. You will see on the right sidebar you can see settings open add your desired field Label, placeholder, description of your choice. We will add Test Title for now. You can even add rules from the rules tab.