re-arrange the user docs (#76)

* re-arrange the user docs

* Minor description edit

* update styles

* fix service links

Co-authored-by: kn0wmad <kn0wmad@protonmail.com>
Co-authored-by: Lucy Cifferello <12953208+elvece@users.noreply.github.com>

site/source/developer-docs/specification/backups.rst

@@ -0,0 +1,41 @@
+.. _service_backups:
+
+=======
+Backups
+=======
+
+Backups are defined by the service developer in the backups section of the Manifest. By default, this action is a command executed within a Docker container.
+
+EmbassyOS provides a system utility for creating backups. This system utility is the `duplicity <https://en.wikipedia.org/wiki/Duplicity_(software)>`_ library that is run inside the Docker image entitled _compat_. 
+
+The path to be backed up can be specified in the Manifest. In the create backup example below, it is the last argument:
+
+.. code:: yaml
+
+    ...
+    # create backup
+    entrypoint: compat 
+    # Arguments to pass into the entrypoint executable. In this example, the full command run will be: `compat duplicity <package-id> /mnt/backup /root/data`
+    args: 
+        - duplicity
+        - <package-id>
+        - /mnt/backup
+        # For duplicity, the backup mount point needs to be something other than `/root`, so we default to `/root/data`
+        - /root/data
+    ...
+
+For restoration purposes, it might be beneficial to ignore certain files or folders. For instance, ignore the shared/public folder that is mounted for dependencies that expose this feature as it causes data inconsistencies on restore.
+
+In this case, create a ``.backupignore`` file in the mounted volume directory. This file contains a list of relative paths to the ignored files.
+
+Example
+-------
+
+The `BTCPay Server wrapper <https://github.com/Start9Labs/btcpayserver-wrapper/blob/master/configurator/src/templates/.backupignore.templates>`_ demonstrates a good use of a backupignore template.
+
+Ultimately, ``/datadir/.backupignore`` gets populated with:
+
+.. code::
+
+    /root/volumes/btcpayserver/start9/public
+    /root/volumes/btcpayserver/start9/shared