Update README a bit

README.rst

@@ -1,6 +1,6 @@
-===============================
+==============
 snap.openstack
-===============================
+==============
 
 Helpers for writing Snaps for OpenStack
 
@@ -8,6 +8,56 @@ This project provides a wrapper for automatically wrapping openstack
 commands in snaps, building out appropriate Oslo configuration and
 logging options on the command line.
 
+This wrapper is used by including a snap-openstack.yaml configuration file
+into the root of a snap.
+
+Setup is executed for all entry points prior to execution snap-openstack
+will assure that templated files are in place and that any directory
+structure in $SNAP_COMMON is created.
+
+```
+setup:
+  dirs:
+    - "{snap_common}/etc/nova.conf.d"
+    - "{snap_common}/etc/nova"
+    - "{snap_common}/logs"
+  templates:
+    "nova-snap.conf.j2": "[snap_common}/etc/nova.conf.d/nova-snap.conf"
+```
+
+snap-openstack.yaml should also declare entry points for the snap:
+
+```
+entry_points:
+  nova-manage:
+    binary: nova-manage
+    config-files:
+      - "{snap}/etc/nova/nova.conf"
+      - "[snap_common}/etc/nova/nova.conf"
+    config-dirs:
+      - "{snap_common}/etc/nova.conf.d"
+    log-file:
+      - "{snap_common}/logs/nova-manage.log"
+```
+
+Executes the following:
+
+```
+nova-manage --config-file=$SNAP/etc/nova/nova,conf \
+            --config-file=$SNAP_COMMON/etc/nova/nova.conf \
+            --config-dir=$SNAP_COMMON/etc/nova.conf.d \
+            --log-file=$SNAP_COMMON/logs/nova-manage.log
+```
+
+entry points are designed to be executed from the snapcraft.yaml apps section
+using:
+
+```
+command: snap-openstack nova-manage
+```
+
+any additional arguments provided will be passed to the underlying binary.
+
 * Free software: Apache license
 * Documentation: http://docs.openstack.org/developer/snap.openstack
 * Source: http://git.openstack.org/cgit/openstack/snap.openstack