README: add ExternalSensor documentation link
Content of the link is here:
https://gerrit.openbmc-project.xyz/c/openbmc/docs/+/41452
Signed-off-by: Josh Lehan <krellan@google.com>
Change-Id: Iab3b015c39c4d870436d2fef910575e31dc2b364
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