Avatar: default slot description note is missing CSS example

[Lukas742]

Issue Description

The description of the default slot of the Avatar component is missing the CSS example:

Receives the desired <img> tag
Note: If you experience flickering of the provided image, you can hide the component until it is being defined with the following CSS:

https://github.com/SAP/ui5-webcomponents/blob/main/packages/main/src/Avatar.ts#L213-L219

Issue Type

• Documentation is unclear
• Documentation is incorrect
• Documentation is missing
• Other

[IlianaB]

Hello @ui5-webcomponents-topic-p , please have a look at this issue about missing documentation.

Missing part is the actual CSS:
ui5-avatar:not(:defined) {
visibility: hidden;
}