build: move LABEL directive in Dockerfile (#269)

Author: jidicula

clang-format-docker/Dockerfile

@@ -1,10 +1,10 @@
-LABEL org.opencontainers.image.description clang-format image
-
 ARG UBUNTU_VERSION
 FROM ubuntu:${UBUNTU_VERSION}
 
 ARG CLANG_FORMAT_VERSION
 
+LABEL org.opencontainers.image.description clang-format image
+
 RUN apt-get update \
 	&& apt-get install --no-install-recommends -y \
 	clang-format-${CLANG_FORMAT_VERSION} \