diff --git a/README.md b/README.md
index dc0105b..7a1e453 100644
--- a/README.md
+++ b/README.md
@@ -8,12 +8,17 @@
 
 ## key features
 
-- runtime re-configurable from d-bus (entity-manager or the like)
+-   runtime re-configurable from d-bus (entity-manager or the like)
 
-- isolated: each sensor type is isolated into its own daemon, so a bug in one
-  sensor is unlikely to affect another, and single sensor modifications are
-  possible
+-   isolated: each sensor type is isolated into its own daemon, so a bug in one
+    sensor is unlikely to affect another, and single sensor modifications are
+    possible
 
-- async single-threaded: uses sdbusplus/asio bindings
+-   async single-threaded: uses sdbusplus/asio bindings
 
-- multiple data inputs: hwmon, d-bus, direct driver access
+-   multiple data inputs: hwmon, d-bus, direct driver access
+
+## sensor documentation
+
+-   [ExternalSensor](https://github.com/openbmc/docs/blob/master/designs/external-sensor.md)
+    virtual sensor