There's a few threads for sharing patreon pages ( here's one!) and I'm pretty sure it'd be fine to include a link to your patreon along with other stuff -- like if you make an introduction post and link to both your comic and patreon, for example.
Making a thread solely to ask people to pledge to your patreon or kickstarter campaign falls under soliciting sales, though, which we want to avoid!
(from the Quick Guide to the Forums)
The basic rule of thumb is that, other than an introduction post to promote your work, topics that you start here should be something the community can chat about -- whether that's asking for help or sharing tips -- and while there is a level of self-promotion and linking to yourself that's totally encouraged here, you don't want to JUST do that and nothing else!
