client: docker/lib_docker: add update feature

Simply rebuilds image without cache because modules are built locally
(meaning, there's no "newer version" image of modules to pull against).

client/src/docker/docker.bash

@@ -65,7 +65,8 @@ function main()
 
   All platforms:
 
-    build       \e[34;3mBuild docker-finance image\e[0m
+    build       \e[34;3mBuild a new docker-finance image\e[0m
+    update      \e[34;3mUpdate an existing docker-finance image\e[0m
     backup      \e[34;3mBackup existing instance image\e[0m
     rm          \e[34;3mRemove image, remove network (also stops container, if running)\e[0m
 
@@ -178,6 +179,9 @@ function main()
     build)
       lib_docker::build "${@:3}"
       ;;
+    update)
+      lib_docker::update "${@:3}"
+      ;;
     up)
       lib_docker::up "${@:3}"
       ;;