T7253: Improve documentation about upgrades with recommendations

Improve the documentation about upgrades and rollbacks with information about how to handle settings.

content/designs/system-updates-and-rollback.md

@@ -742,7 +742,7 @@ and the signature is checked for the extracted commit tree.
 
 ### Configuration
 
-As described in [preferences and persistance]( {{< ref preferences-and-persistence.md >}} )
+As described in [preferences and persistence]( {{< ref preferences-and-persistence.md >}} )
 there different types of settings which should be preserved across updates by
 either keeping them intact of updating them to match the new logic of the
 application.
@@ -755,7 +755,7 @@ is also left as read-write.
 
 As explained, during an upgrade, a new commit is applied on the `OSTree` repo,
 which modifies the read-only partitions, but does not modify the read-write
-ones. To handle the upgrade of system settigs stored in `/etc` a copy of its
+ones. To handle the upgrade of system settings stored in `/etc` a copy of its
 default values is kept in `/usr/etc` which is updated with the new commit.
 hanks to this information `OSTree` can detect the files that have been changed
 and apply a 3-way merge, to update the `/etc`.
@@ -764,8 +764,8 @@ This process allows to update settings to new defaults for files that were not
 modified and keep intact those that were.
 
 Applications are encouraged to handle settings adaptation to new version
-following the guidelines described in [User and user data management]( {{< ref "#user-and-user-data-management" >}} )
-and [Preference and Persistance]( {{< ref preferences-and-persistence.md >}} ).
+following the guidelines described in [user and user data management]( {{< ref "#user-and-user-data-management" >}} )
+and [preference and persistence]( {{< ref preferences-and-persistence.md >}} ).
 
 ### Error handling