I mean that you are one of several. Hence the running joke is the "Rust Evangelism Strike Force" and not "that one rust guy."

An evangelist/growth focused role is exactly what a promoter is. If you spend large numbers of typical work-hours, which I'm assuming you're paid for, on social media to promote something, like Rust, or you go to conferences and events to speak publicly in promotion of something like Rust, then a "paid promoter" seems like a pretty accurate description.

Is that disparaging? Is that not what you are doing right now?