update

services/settings/README.md

@@ -1,10 +1,28 @@
 # Settings
 
-When using oCIS, the requirement to store settings arises. This extension provides functionality
-for other extensions to register new settings within oCIS. It is responsible for storing the respective
-settings values as well.
+The "settings" service provides functionality for other services to register
+new settings within oCIS. It is also responsible for storing the respective settings
+values as well.
 
-{{< mermaid class="text-center">}}
+The "settings" service is currently used for
+* managing the users' "profile" settings. E.g. the language and the Email notification
+  settings
+* managing the possible user roles and their respecitve permssions
+* managing the assignment of roles to users
+
+The "settings" service supports two different backends for persisting the data. The backend
+can be set using `SETTINGS_STORE_TYPE` environment variable. Supported values are:
+
+* `metadata`: The default. This backend persists the settings data via the `storeage-system` service
+* `filesystem`: This backend persists the settings data in a directory on the local filesystem.
+  The directory can be configured with `SETTINGS_DATA_PATH`. This backend is not suitable for running
+  multiple intances of the `settings` service in a scale-out deployment. It should be considered
+  deprecated.
+
+<!--- Note: The diagramm is outdate, leaving it here for a future rework
+The diagram shows how the settings service integrates into oCIS:
+
+```mermaid
 graph TD
     ows ---|"listSettingsBundles(),<br>saveSettingsValue(value)"| os[ocis-settings]
     owc ---|"listSettingsValues()"| sdk[oC SDK]
@@ -12,12 +30,15 @@ graph TD
     sdks ---|"yes"| os
     sdks ---|"no"| defaults[Use set of<br>default values]
     oa[oCIS services<br>e.g. ocis-accounts] ---|"saveSettingsBundle(bundle)"| os
-{{< /mermaid >}}
+```
+-->
 
 The diagram shows how the settings service integrates into oCIS:
 
-**Settings management:**
-- oCIS services can register *settings bundles* with the ocis-settings service.
+## Settings Management
 
-**Settings usage:**
-- Extensions can query ocis-settings for *settings values* of a user.
+oCIS services can register *settings bundles* with the ocis-settings service.
+
+## Settings Usage
+
+Services can query ocis-settings for *settings values* of a user.