Update README to describe configuration file format

Bug-AGL: SPEC-3815

Change-Id: I61d0fdea053ef1bd4f6b78838590636b6ce0ca6c
Signed-off-by: Damian Hobson-Garcia <dhobsong@igel.co.jp>

1 files changed, 31 insertions, 7 deletions

diff --git a/README.md b/README.md
index aa6cc2d..f9a7650 100644
--- a/README.md
+++ b/README.md
@@ -24,18 +24,33 @@ The basic build procedure is as follows:
 
 `<build_dir>` can be any directory name, but `build` is commonly used.
 
-## Running
+## Configuration
 
-Once installed, running the following command will start the DRM Lease Manager daemon
+The drm-lease-manager configuration file allows the user to specify the mapping
+of DRM connectors to DRM leases. The location of the configuration file can
+be specified with the `--config` command line option.
 
-    drm-lease-manager [<path DRM device>]
+The configuration file consists of a list of lease definitions, containing a name
+of the lease and a list of the included connector names.
 
-If no DRM device is specified, `/dev/dri/card0` will be used.  
-More detailed options can be displayed by specifying the `-h` flag.
+Each list entry is of the following form:
 
-### Lease naming
+```toml
+[[lease]]    
+name="My lease"
+connectors=["connector 1", "connector 2"]
+```
+* Note: quotes around all string values are mandatory.
+
+This will create a lease named `My lease` and add the two connectors `connector 1` and
+`connector 2` to the lease.  
+If there is no connector with either of the names exists on the system, that name
+will be omitted from the lease.
 
-One DRM lease will be created for each connector on the DRM device (up to the number of available CRTCs).
+### Default configuration
+
+If no configuration file is specified one DRM lease will be created for each connector
+on the DRM device (up to the number of available CRTCs).
 
 The names of the DRM leases will have the following pattern:
 
@@ -44,6 +59,15 @@ The names of the DRM leases will have the following pattern:
 So, for example, a DRM lease for the first LVDS device on the device `/dev/dri/card0` would be named
 `card0-LVDS-1`.
 
+## Running
+
+Once installed, running the following command will start the DRM Lease Manager daemon
+
+    drm-lease-manager [<path DRM device>]
+
+If no DRM device is specified, `/dev/dri/card0` will be used.  
+More detailed options can be displayed by specifying the `-h` flag.
+
 ### Dynamic lease transfer
 
 When `drm-lease-manager` is started with the `-t` option, the