Update keps/sig-node/3542-cri-image-pulling-with-progress-notificatio…

…n/README.md

Co-authored-by: Mike Brown <brownwm@us.ibm.com>

keps/sig-node/3542-cri-image-pulling-with-progress-notification/README.md

@@ -72,7 +72,7 @@ Introduce new CRI API call for downloading a container image with possibility of
 reports being sent back to requestor and / or no-progress timeout. It should be possible to use
 both the progress reporting and no-progress timeout together as well as separately. For instance,
 the runtime should send back messages about image pulling progress with information
-on how much data was downloaded and what is the current estimated total size of download, and
+on how much data was downloaded and, if known, what is the current estimated total size of download, and
 report a failure at any point after M consecutive seconds of no data being downloaded.
 
 ## Motivation