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
version.
3 jobs from 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)
Status Job ID Name Coverage
  Test
passed #1941
memopol
docs build

00:03:32

passed #1940
memopol
qa checks

00:05:22

passed #1939
memopol
unit tests

00:09:25

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