Add an inline max-width to banniere-en.png on home

Currently the image have a way too big width.
This create a big horizontal scrolling on the homepage.
This probably needs a better fix, but this way we fix the current
3 jobs for 202-the-homepage-have-an-image-with-a-way-too-high-width in 18 minutes and 20 seconds (queued for 2 minutes and 38 seconds)