Update Docker LABEL to standard notation

Author: ain

Dockerfile

@@ -1,7 +1,7 @@
 FROM golang:latest
 
-LABEL version="0.0.1"
-LABEL maintainer="Ain Tohvri <ain@flashbit.net>"
+LABEL org.opencontainers.image.authors="Ain Tohvri <ain@flashbit.net>" \
+      org.opencontainers.image.version="0.1.0"
 
 RUN go install github.com/ysugimoto/falco/cmd/falco@latest