proto: add module name

We now have auto-generated docs at
https://buf.build/certusone/wormhole/docs/main/publicrpc.v1

Change-Id: Ic29f8fc67013a605ec33732f048a7b9361f5e60d

buf.yaml

@@ -1,5 +1,6 @@
 ---
 version: v1beta1
+name: buf.build/certusone/wormhole
 deps:
   - buf.build/beta/googleapis
   - buf.build/grpc-ecosystem/grpc-gateway