build: add pull flag to force image pulling

Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com>
Upstream-commit: 054e57a622e6a065c343806e7334920d17a03c5b
Component: engine

components/engine/docs/sources/reference/api/docker_remote_api_v1.16.md

@@ -1156,6 +1156,7 @@ Query Parameters:
         the resulting image in case of success
 -   **q** – suppress verbose build output
 -   **nocache** – do not use the cache when building the image
+-   **pull** - attempt to pull the image even if an older image exists locally
 -   **rm** - remove intermediate containers after a successful build (default behavior)
 -   **forcerm - always remove intermediate containers (includes rm)
 

components/engine/docs/sources/reference/commandline/cli.md

@@ -312,6 +312,7 @@ To kill the container, use `docker kill`.
 
       --force-rm=false     Always remove intermediate containers, even after unsuccessful builds
       --no-cache=false     Do not use cache when building the image
+      --pull=false         Always attempt to pull a newer version of the image
       -q, --quiet=false    Suppress the verbose output generated by the containers
       --rm=true            Remove intermediate containers after a successful build
       -t, --tag=""         Repository name (and optionally a tag) to be applied to the resulting image in case of success