I think there is two options
You can make your image with alt text clickable as a link.
Or you can provide a full text with your link. It should be catched by screen reader
<a href="https://community.rstudio.com">Community Rstudio</a>
Community Rstudio
Markdown syntax should work
[Community Rstudio ](Https://community.rstudio.com)
Community Rstudio
Did you already try that?