docs: 📚 add accessibility info to sd-prose

[coraliefeil]

Description

Was ist der Unterschied zwischen <strong> und <b>? https://blogs.uni-bielefeld.de/blog/internetservice/entry/was_ist_der_unterschied_zwischen

We only offer <strong> in sd-prose.

-> Add the accessibility info to our documentation to raise awareness here

Where to put the documentation

DoR

• [x] Item has business value
• [ ] Item has been estimated by the team
• [x] Item is clear and well-defined
• [x] 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

[coraliefeil]

"We advise against using bold , and italic tags when you want to emphasize a word or passage."

https://help.siteimprove.com/support/solutions/articles/80000448460-accessibility-the-use-of-emphasis-in-text