Add bash completion for `builder prune`

Signed-off-by: Harald Albers <github@albersweb.de>

contrib/completion/bash/docker

@@ -1202,6 +1202,41 @@ _docker_build() {
 }
 
 
+_docker_builder() {
+	local subcommands="
+		prune
+	"
+	__docker_subcommands "$subcommands" && return
+
+	case "$cur" in
+		-*)
+			COMPREPLY=( $( compgen -W "--help" -- "$cur" ) )
+			;;
+		*)
+			COMPREPLY=( $( compgen -W "$subcommands" -- "$cur" ) )
+			;;
+	esac
+}
+
+_docker_builder_prune() {
+	case "$prev" in
+		--filter)
+			COMPREPLY=( $( compgen -S = -W "description id inuse parent private shared type until unused-for" -- "$cur" ) )
+			__docker_nospace
+			return
+			;;
+		--keep-storage)
+			return
+			;;
+	esac
+
+	case "$cur" in
+		-*)
+			COMPREPLY=( $( compgen -W "--all -a --filter --force -f --help --keep-storage" -- "$cur" ) )
+			;;
+	esac
+}
+
 _docker_checkpoint() {
 	local subcommands="
 		create
@@ -5348,6 +5383,7 @@ _docker() {
 	shopt -s extglob
 
 	local management_commands=(
+		builder
 		config
 		container
 		context