add list of options

docs/source/configuration.rst

@@ -21,7 +21,33 @@ self-explanatory.
 
 Each section corresponds with a snapper configuration. Add additional sections to add
 other snapper configurations to be snapshotted. By default, only the root configuration
-is snapshotted.
+is snapshotted. Additionally you can add a section named ``DEFAULT`` with options that
+apply to all snapper configurations unless overridden in a later section.
+
+Each section can have the following entries:
+
+**desc_limit** - integer; maximum length of description string before being truncated.
+Default: 72
+
+**important_packages** - list of strings; names of packages that if involved in a pacman
+transaction will add ``important=yes`` to the snapper userdata for the pair of
+snapshots. Default: []
+
+**important_commands** - list of strings; parent commands that will add
+``important=yes`` to the snapper userdata for the pair of snapshots. Default: []
+
+**pre_description** - string; description for the pre snapshot. Default: the parent
+command that called the pacman hook.
+
+**post_description** - string; description for the post snapshot. Default: space
+separated list of packages that were installed, upgraded, or removed.
+
+**snapshot** - boolean; whether or not to snapshot the configuration. Default: True for
+``root`` configuration; False otherwise.
+
+**userdata** - list of strings; key-value pairs that will be added to the userdata for
+the pair of snapshots. Default: []
+
 
 Environment Variables
 ---------------------