QDoc generates warnings for images that do not have an alternate-text
associated with it. Alt-text is required for to increase accessibilty
options.
This patch adds alt-text to images in the Qt Network
Fixes: QTBUG-135122
Pick-to: 6.9 6.8
Change-Id: I690f1d381ef5a9052e189dd1f3906243df557da0
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>
ae6ba06e55