README: Add notes about delete mechanism blob option

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: Id4634117f88727c91d2422d0cd0062f8c383c0ee
diff --git a/README.md b/README.md
index 512357c..1fc6027 100644
--- a/README.md
+++ b/README.md
@@ -92,6 +92,12 @@
 `--enable-aspeed-lpc`  | Use with ASPEED parts.
 `--enable-nuvoton-lpc` | Use with Nuvoton parts.
 
+There are also options to control an optional clean up mechanism.
+
+Option                    | Meaning
+------------------------- | -------
+`--enable-cleanup-delete` | Provide a simple blob id that deletes artifacts.
+
 ### Internal Configuration Details
 
 The following variables can be set to whatever you wish, however they have