Merge pull request #2810 from thaJeztah/19.03_backport_docs_maintainer

[19.03 backport] Replace deprecated instruction
Upstream-commit: fd3371eb7df1adeceff5935cf3ade0576a0f48d5
Component: cli

Author: silvin-lubecki

components/cli/docs/reference/commandline/pull.md

@@ -160,7 +160,7 @@ Digest can also be used in the `FROM` of a Dockerfile, for example:
 
 ```dockerfile
 FROM ubuntu@sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2
-MAINTAINER some maintainer <maintainer@example.com>
+LABEL maintainer="some maintainer <maintainer@example.com>"
 ```
 
 > **Note**

components/cli/man/src/image/pull.md

@@ -111,7 +111,7 @@ pull the above image by digest, run the following command:
 Digest can also be used in the `FROM` of a Dockerfile, for example:
 
     FROM ubuntu@sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2
-    MAINTAINER some maintainer <maintainer@example.com>
+    LABEL maintainer="some maintainer <maintainer@example.com>"
 
 > **Note**: Using this feature "pins" an image to a specific version in time.
 > Docker will therefore not pull updated versions of an image, which may include