Explain what the VIRTUAL SIZE means
Docker-DCO-1.1-Signed-off-by: Sven Dowideit (github: SvenDowideit)
@@ -796,6 +796,10 @@ decrease disk usage, and speed up `docker build` by
allowing each step to be cached. These intermediate layers are not shown
by default.
+The `VIRTUAL SIZE` is the cumulative space taken up by the image and all
+its parent images. This is also the disk space used by the contents of the
+Tar file created when you `docker save` an image.
+
An image will be listed more than once if it has multiple repository names
or tags. This single image (identifiable by its matching `IMAGE ID`)
uses up the `VIRTUAL SIZE` listed only once.
