The main feature list should provide a short overview of the, well,
main features. While enterprise support *is* a main and important
feature, it's not the place here to describe things like personal
volume/ngo/... offers and the like.
Move parts of it to getting help, which lacked mentioning the
enterprise support too and is a good place to describe the customer
portal.
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>