Update customer.md

Fixed typo

foundation/www/docs/user/manual/en/CRM/customer.md

@@ -46,7 +46,7 @@ to create an Account in another Company, just change the Company value and
 “Save” the Customer again.
 
 By default, the system does not generate an account for every customer. All
-Customers can be booked in one account called Debtors. In order to manage a
+Customers can be booked in one account called Debitors. In order to manage a
 separate account for each customer, you have to first create the account under
 Accounts Receivable in the [Chart of Accounts](/docs/user/manual/en/accounts/chart-of-accounts.html) and then add it on the customer's
 form accounts table.