The link was actually removed automatically because jjonas0099 is a new member; all links are removed until some number of posts have been made by a user (I think it may be ten posts). This is to help combat spamming, particularly spamming that is attempting to boost a site's Google rank by creating lots of links to the site.
So far as I'm aware, pertinent links to other forums are not generally prohibited, the same as for other websites in general. The "Forum Rules" as linked at the top of the page have no such restriction. Posts that are advertisements for businesses (including websites) are prohibited, though, and this post did appear to me to be questionable in that regard.
