Update README with usage information

README.md

@@ -1,5 +1,67 @@
-Glance Snap
+# Glance Snap
-===========
 
-This repository contains the source code of the snap for the
+This repository contains the source code of the snap for the OpenStack Image
-OpenStack Image service, Glance.
+service, Glance.
+
+## Installing this snap
+
+The glance snap can be installed directly from the snap store:
+
+    sudo snap install [--edge] glance
+
+## Configuring Glance
+
+Snaps run in an AppArmor and seccomp confined profile, so don't read
+configuration from `/etc/glance` on the hosting operating system install.
+
+This snap supports configuration via the $SNAP\_COMMON writable area for the
+snap:
+
+    etc
+    ├── glance
+    │   ├── glance-api.conf
+    │   └── glance-registry.conf
+    └── glance.conf.d
+        ├── database.conf
+        ├── glance-snap.conf
+        └── keystone.conf
+
+The glance daemons (api and registry) can be configured in a few ways.
+
+Firstly each daemon will detect and read `etc/glance/glance-<daemon>.conf`
+if it exists so you can just place all configuration in this file for each
+daemon.
+
+Alternatively all daemons will load all configuration files from
+`etc/glance.conf.d` - in the above example, database and keystone authtoken
+onfiguration is shared across both daemons using configuration snippets in
+separate files in `etc/glance.conf.d`.
+
+For reference, $SNAP\_COMMON is typically located under
+`/var/snap/glance/common`.
+
+## Managing Glance
+
+Currently all snap binaries must be run as root; for example, to run the
+glance-manage binary use:
+
+    sudo glance.manage
+
+## Restarting Glance services
+
+To restart all glance services:
+
+    sudo systemctl restart snap.glance.*
+
+or use the individual service name:
+
+    sudo systemctl restart snap.glance.api
+    sudo systemctl restart snap.glance.registy
+
+## Support
+
+Please report any bugs related to this snap on
+[Launchpad](https://bugs.launchpad.net/snap-glance/+filebug).
+
+Alternatively you can find the OpenStack Snap team in `#openstack-snaps`
+on Freenode IRC.