control:docs: Create groups.md
This describes the groups.json file.
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I8cba2159dbd56b0e631dc378ccfc38a6cf9b9a6c
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+# groups.json
+
+This file contains an array of group definitions. In this usage, a group
+refers to a group of D-Bus objects that all of the same D-Bus path and
+interface, and are acted upon by actions and triggers in events.json.
+Only the D-Bus objects paths are specified in this file, the interface and
+properties are specified at the time of usage in events.json.
+
+## JSON example
+
+```
+[
+ {
+ "name": "occ objects",
+ "service": "org.open_power.OCC.Control",
+ "members": [
+ "/org/open_power/control/occ0",
+ "/org/open_power/control/occ1"
+ ]
+ }
+]
+```
+
+## Attributes
+
+### members
+An array of the D-Bus object paths that are in the group. Required.
+
+### name
+The group name. This is how the group is referenced in events.json.
+Required.
+
+### service
+If known, the D-Bus service name that provides these D-bus objects. All
+members of the group must be hosted by the same service for this to be used.
+This provides performance improvements in certain cases. Optional.