Multilingual slug setup
The problem you're probably facing isn't that URLs like

http://example.com/en/news/example
http://example.com/fr/nouvelles/exemple

don't work, but that you're not getting the sections' index pages to load because they're just a index.html file in your templates/news/ folder (→ routing case 6 in https://craftcms.com/docs/routing).

For a multi locale setup with translated slugs it's recommended to not rely on "URI to template matching" at all and create an entry or category for every page, so Craft sets up the routes for all the translated slugs automatically (→ routing case 4).

In your case you'd just create an entry for your News index page, e.g through a single section. In the single section's settings set up the URLs for your locales and route them to your template.