Update readme.md

Author: lerndevops

docker/images/readme.md

@@ -109,6 +109,10 @@ how to push images offline ( docker save & docker load )
 Advanced image concepts
 =======================
    find dangling images
- 
-   docker images -f dangling=true
-   docker image prune --dangling=true
+      docker images -f dangling=true
+      docker image prune --dangling=true
+
+   Inspect image metadata:
+      docker image inspect nginx:1.14.0
+      docker image inspect nginx:1.14.0 --format "{{.Architecture}}"
+      docker image inspect nginx:1.14.0 --format "{{.Architecture}} {{.Os}}"