Improve document for the --enable-universal-plane optionHEADmaster

At 901f400634395f3a73648b1515de7f4f4c5a831f commit add
--enable-universal-plane command line option.

This patch adds document for the --enable-universal-plane option.

Bug-AGL: SPEC-5132

Change-Id: Ia5234da87d07dbdf3a9f068b3d1644b4ec26838a
Signed-off-by: Naoto Yamaguchi <naoto.yamaguchi@aisin.co.jp>

1 files changed, 13 insertions, 0 deletions

diff --git a/README.md b/README.md
index 97e9274..6adfcdb 100644
--- a/README.md
+++ b/README.md
@@ -30,11 +30,22 @@ 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.
 
+The drm-lease-manager has two lease modes.  1st one is a single-plane mode, and the other is a multi-plane mode.
+
+A single-plane mode supports only one plane per output connector.  On the other hand, it worked various DRM drivers.
+
+A multi-plane mode supports one or more planes per output connector.
+On the other hand, this mode did not work some DRM driver such as rockchip without strict connector configuration.
+
+The default is single-plane mode.  When you want to use multi-plane mode, use `--enable-universal-plane` command line option.
+
 The TOML configuration file consists of a list of lease definitions
 and a set of optional connector configurations.
 
 ### Lease definitions
 
+**This configuration is required both single-plane mode and multi-plane mode.**
+
 Each list entry is of the following form:
 
 ```toml
@@ -61,6 +72,8 @@ necessary.
 
 ### Connector configuration
 
+**This setting is optional not a mandatory.  That setting is using in multi-plane mode.**
+
 Each connector that appears in the `connectors` field of a lease configuration
 can be additionally configured in a table with the connector name.  
 To continue the example above, the connector configuration could be as follows: