De la rédaction à la communication technique: make text clearer

Change "produit" to "existant" to avoid confusion between "product" and
"produced".

Signed-off-by: Olivier Carrère <carrereo@gmail.com>
Acked-by: Angela Cristina <acristina@redaction-technique.org>
De la rédaction à la communication technique: move paragraph

Move paragraph about "valorisation" to display it in a more relevant context.

Signed-off-by: Olivier Carrère <carrereo@gmail.com>
Acked-by: Angela Cristina <acristina@redaction-technique.org>
De la rédaction à la communication technique: remove last part

Remove last subsection, no longer in line with new website version.

Signed-off-by: Olivier Carrère <carrereo@gmail.com>
Acked-by: Angela Cristina <acristina@redaction-technique.org>