Citation plugin: change Markdown primary citation template to return "Author et al., YYYY"

Dear all,

I would like to change the appearance of Markdown citations to “Author et al., YYYY”.
The default is “[@{{citekey}}]”, which I do not find very appealing.

I have searched for quite a while, but could not find a straight forward way of how to achieve this. I would highly appreciate every hint or link to a related topic.