Update file versioning retention policy details

Clarified version retention policy in documentation. Add the information that we always keep the latest version in each time window.

Signed-off-by: Björn Schießle <bjoern.schiessle@nextcloud.com>

Author: schiessle

admin_manual/configuration_files/file_versioning.rst

@@ -15,7 +15,7 @@ pattern used to delete old versions:
 * After the first 30 days Nextcloud keeps one version every week
 
 The versions are adjusted along this pattern every time a new version is 
-created.
+created. Nextcloud will always keep the latest version in each of the time windows.
 
 The Versions app never uses more than 50% of the user's currently available 
 free space. If the stored versions exceed this limit, Nextcloud deletes the 
@@ -68,4 +68,4 @@ Deactivate background job: ``occ config:app:set --value=no files_versions backgr
 
 Activate background job: ``occ config:app:delete files_versions background_job_expire_versions``
 
-Expire versions: ``occ versions:expire`` or ``occ versions:expire --quiet`` (without the progress bar)
+Expire versions: ``occ versions:expire`` or ``occ versions:expire --quiet`` (without the progress bar)