Admittedly the web version of WhatsApp has always felt very barebones in the sense in the sense that the mobile version had more features than it. However this update should change that as users will now be able to send documents to one another, but we should point out that this will require all WhatsApp users to have the latest version of the app.
This means if for some reason the person you’re sending a document to does not have the latest version of WhatsApp that supports document sharing, then the feature would be moot. The same will apply to you. That being said, it looks like the desktop version of WhatsApp (that was launched a few days ago) has been updated with the same features, so it seems that all WhatsApp users will be able to share documents across mobile devices, the web, and the desktop.