[FIX] sales_team: spellchecking module description
[FIX] product, sale: access rights for product.price.history

Granting read-only access to Sales/Accounting Users is useless
as all employees already have it - removed. On the other hand
Sales Managers need write access to it in order to create
products, and they need it even when `sale` is not installed,
e.g. with `account` only.
Moved this access right to `product` module. The Sales
Manager group is defined in `base`, so that works.