Update LED Group README.md

Add assertion made in https://gerrit.openbmc-project.xyz/#/c/8086/
    - enclosure_identify has the special property that it is routed
    from the ipmi command chassis identify.

Change-Id: Ic9a5d46b9ff2235f8a197e4ca4e4797d1bf72ce8
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/xyz/openbmc_project/Led/README.md b/xyz/openbmc_project/Led/README.md
index bb6aff5..254e587 100644
--- a/xyz/openbmc_project/Led/README.md
+++ b/xyz/openbmc_project/Led/README.md
@@ -93,6 +93,10 @@
 bmc_booted:
 power_on:
 ```
+
+For the IPMI command "chassis identify" to function, **enclosure_identify** must
+also be implemented.
+
 ## Understanding Physical LEDs
 
 It is always **recommended** that external users use **only** the LED groups.