Add snippet about data export

docs/admin/maintenance/dataexport.md

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+---
+sidebar_position: 5
+id: dataexport
+title: "Data Export"
+description:: "Information about data export."
+---
+
+#  Data Export
+
+## Files
+
+OpenCloud stores files by default in the file system under the path `/var/lib/opencloud/`. Any other path that is local to the server instance running the OpenCloud backend can be configured as alternative path using the environment variable `OC_BASE_DATA_PATH`.
+
+Files and folders are stored in a folder structure underneath that base path in folder `data/storage/users/`. 
+
+Files are by default stored in the original format and not encrypted.
+
+## Metadata
+
+File metadata is stored in the file system with every file. It is either in the extended file attributes (user namespace) or in a separate metadata file. That file is in the [MessagePack](https://msgpack.org) format and can be read with the CLI tools for that file type.
+
+## Configuration
+
+Configuration files are written as yaml files by default under `$HOME/.config/OpenCloud`.
+
+## Other 
+
+Other, non-file-related metadata such as links is also stored under the general data base path, in JSON format.
+