taskid-3184602.
16.0 -> Change extra fees category to :ref: main page payment provider
16.2 -> Remove Odoo credentials section
Remove PDT identity token
Remove merchant ID note
Remove test mode section on environment test
Took the opportunity to redo the whole page.
closesodoo/documentation#4396
Signed-off-by: Tom Aarab (toaa) <toaa@odoo.com>
