In this case I honestly do think that the OP should let the wedding guest know that she is serving a vegan menu, because she isn't a vegan of vegetarian. If I was going to the wedding of a person I knew didn't eat meat then I wouldn't be surprised that they didn't serve it , but if I'm going to a wedding of a person who i knew ate meat I would be quite surprised at a vegan menu.
I'm with Visiting Crazy Town. I would expect a vegan or vegetarian bride/groom to have a vegan/vegetarian reception, and more importantly, I would plan accordingly. For me this would probably mean eating before I come to the ceremony/reception, not because I think vegan/vegetarian is "weird" but because I am unaccustomed to eating that way, and to be sure that I ate enough to feel comfortable and enjoy myself would take more effort than I want to give (e.g., will I like that, can I eat this, is it too spicy, have I earn enough protein to stay full, etc.). I'd rather focus my energies on my friends' wedding and celebration. A more adventurous eater might plan differently.
I would not be expecting omnivore friends to offer an exclusively vegan menu, and if surprised by it there would be much more focus, for me, on the food and whether I can eat sufficiently than I would like. It might even mean I'd have to leave early to eat, which would be very disappointing.
The thing is, in an effort to avoid having to listen to some of the bellyachers (who, lets face it, will complain about something no matter what you do) you may be taking away the ability of gracious guests to plan appropriately for their own needs so they can celebrate with you as they wish.
I would post the menu on my website, and when asked about the caterer I would mention that they are vegan, and the food is wonderful, and you are so excited to share this new find with everyone. The word will get around, and people will have the info they need.