update readme and usage

usage.js

@@ -0,0 +1,47 @@
+const usage = `Synopsis
+
+    swm
+    swm [monitor-1..montior-n]
+    swm --profile external
+    swm --list
+
+Description
+
+    To turn on/off connected/disconnected monitors.
+
+    If no monitors are specified all connected monitors will be turned on and
+    placed from left to right in alphabetical order of their name.
+
+    If monitors monitor-1..monitor-n are specified these monitors will be turned
+    on and place them from left to right in the order given.
+
+    --profile profilename or -p profilename
+        If a profile is specified, the configured monitors will be turned on.
+
+    --postCmd "some cmd"
+
+        A post command is executed after switching the monitors.  This is usefull to
+        tell your window manager to re-detect monitors, e.g. for herbstluftwm
+        herbstclient reload.
+
+    -l or swm --list
+
+        List all devices with the connectivity status.
+
+Configuration
+
+The configuration can be placed in $XDG_CONFIG_HOME/switchmon/config.json in
+the form of
+
+{
+    "postCmd": "some command",
+    "profiles": {
+        "internal": ["LVDS1"],
+        "external": ["HDMI1"],
+        "dual": ["LVDS1", "HDMI1"]
+    }
+}
+
+`;
+
+module.exports = usage;