[IMP] install/maintain: update content of upgrade SLA

The maintenance fees cover the maintenance of the custom code (whoever
did it) and are not specifically dedicated to custom code written by
Odoo development teams

content/administration/upgrade.rst

@@ -225,15 +225,14 @@ Service Level Agreement
 What is covered by the Enterprise Licence?
 ------------------------------------------
 
-Databases hosted on Odoo’s Cloud platforms (Odoo Online and Odoo.sh) or On-Premise (Self-Hosting)
+Databases hosted on Odoo's Cloud platforms (Odoo Online and Odoo.sh) or On-Premise (Self-Hosting)
 enjoy the following services at all times.
 
 The upgrade of:
 
 * standard applications
 * Studio customization (as long as the :guilabel:`Studio` app is still active)
-* customizations done by our consulting and developer services *if* they are covered by a
-  ‘Maintenance of Customisations’ subscription
+* customizations *if* they are covered by a "Maintenance of Customizations" subscription
 
 The Upgrade Service is limited to your database's technical conversion and adaptation (standard
 modules and data) to make it compatible with the targeted version.