README: Add reboot default configuration option

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: Ic4052830f9c00d1cc9f2df8d78a7a5fe9de7122b
diff --git a/README.md b/README.md
index fe1bfcb..a5008ff 100644
--- a/README.md
+++ b/README.md
@@ -98,6 +98,13 @@
 ------------------------- | -------
 `--enable-cleanup-delete` | Provide a simple blob id that deletes artifacts.
 
+If the update mechanism desired is simply a BMC reboot, a platform can just
+enable that directly.
+
+Option                   | Meaning
+------------------------ | -------
+`--enable-reboot-update` | Enable use of reboot update mechanism.
+
 ### Internal Configuration Details
 
 The following variables can be set to whatever you wish, however they have