docs: 📚 add template button label to sd-button with sd-icon

[karlbaumhauer]

Description

In case a button uses an icon and has only limited space, the sd-icon and sd-button label can be combined in order to improve a11y even with shorter texts.

Template:

This template should show a button (eg. printing a summary), where the print icon has the lable "print" and the label "summary" in English and German (to show the order is critical here).

This will make the buttons readable for people with "normal" vision but also offers detailed information for screen readers.

<sd-button>summary<sd-icon name="system/print" slot="icon-left">print</sd-icon></sd-button>
<sd-button>Zusammenfassung<sd-icon name="system/print" slot="icon-right">Drucken</sd-icon></sd-button>

Where to put the documentation

DoR

• Item has business value
• Item has been estimated by the team
• Item is clear and well-defined
• Item dependencies have been identified

DoD

• Documentation has been created/updated (if applicable)
• Migration Guide has been created/updated (if applicable)
• Relevant stories (Features, A11y) are created/updated
• Implementation works successfully on feature branch