Updated push.md with progress bar info
@@ -36,6 +36,10 @@ image and tag names.
Killing the `docker push` process, for example by pressing `CTRL-c` while it is
running in a terminal, terminates the push operation.
+Progress bars are shown during docker push, which show the uncompressed size. The
+actual amount of data that's pushed will be compressed before sending, so the uploaded
+ size will not be reflected by the progress bar.
+
Registry credentials are managed by [docker login](login.md).
### Concurrent uploads
