Add maintainer label for docker file (#2658)

* Add maintainer label for docker file

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

* update

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

Dockerfile

@@ -1,5 +1,6 @@
 FROM alpine:3.6
-MAINTAINER Thomas Boerger <thomas@webhippie.de>
+
+LABEL maintainer="The Gitea Authors"
 
 EXPOSE 22 3000
 

Dockerfile.aarch64

@@ -1,5 +1,7 @@
 FROM multiarch/alpine:aarch64-v3.6
 
+LABEL maintainer="The Gitea Authors"
+
 EXPOSE 22 3000
 
 RUN apk --no-cache add \

Dockerfile.rpi

@@ -1,5 +1,6 @@
 FROM multiarch/alpine:armhf-v3.6
-MAINTAINER Thomas Boerger <thomas@webhippie.de>
+
+LABEL maintainer="The Gitea Authors"
 
 EXPOSE 22 3000