This PR change the cheat sheet of the accounting documentation.
Change done:
* Change name of the file: memento to cheat_sheet
* Adding explanation to the doc (Ex: Invoices and bills status)
* Correcting some sentences
closesodoo/documentation#3045
Task-id: 2847663
Signed-off-by: Castillo Jonathan (jcs) <jcs@odoo.com>