I did a similar thing to you, but when I hit the sign it bounced in and out for the entire length of my awning as I drove past so I had about 6 cuts at different depths across the length of my awning. I bought the Camco awning tape others have mentioned and used it to tape both sides of the awning fabric (top and bottom) for each of the gashes across my awning. I ended up patching over about 20 total gashes.
The tape has been on the awning for several months and we were able to camp through the rainy northwest winter and it has survived. It's definitely stickier than packing tape--it's more like duct tape, but clear so you can't really see it unless you get close.
2013 Forest River Cascade 22BH
2014 Chevrolet 3500 Duramax CC SB 4X4