The template
Subject: A source for your {article topic} article
Hi {first name},
I was reading {article title} and the part about {specific section} was useful.
We published {your page title}, which {what it adds that the article doesn't: data, a template, a walkthrough}. It might give readers a next step right after "{a short quote from the sentence where it fits}".
If you think it adds something, would you consider linking it there? No problem if not.
Thanks,
{your first name}