Here is essentially the same fix, but using the VS Code UI which may make it easier for some people - especially if your new to this and your settings.json file has not been generated yet.
In VS Code go to File -> Preferences -> Settings
Once there you can switch to the 'Workspace' tab if you want this setting to only be for this project/workspace, or stick with the 'User' tab if you want this on all projects/workspaces.
Open the 'Extensions' item in the list and click on 'Emmet'.
Under 'Include Languages' click the 'Add Item' button. Fill it in with:
Item: django-html
Value: html
and click the 'OK' button.
This will add the setting for you to your settings.json file, or generate you a new settings.json file if you don't have one.

Note: To get the autocomplete/generate to work you might need to type your tag without the brackets e.g. li (not <li>), then press enter to get <li></li>