Hi Romain, the rich text widget lets you embed Markdown content into your dashboards. But reports such as the table and repeater widgets do not support rendering markdown content at this time.
You can find more details on markdown here:
https://www.gooddata.com/blog/rich-text-in-dashboards/
However, GoodData Cloud is constantly evolving, and future releases may include support for dynamic markdown rendering in widgets, and I will be happy to mark this as “Product feedback” on your behalf if this is something that you’d like to see in the future.