That’s a great idea to automate it in some way @maique! Currently you’re correct — there’s no way to do this at the moment because Write.as adds rel=nofollow to links by default. @matt outlines the reasons in this forum post:
However, in that same post he mentions that removing the rel=nofollow could be a possibility for those with a Pro subscription. I think that’s more than fair.
I’m curious to see what other people thing of that idea. For one, having rel=me would open the door for Write.as to be one step closer to implementing some IndieWeb standards like IndieAuth and WebMentions