fix JSON syntax in readme file

hexadecimal numbers are not a valid json values, this commit fixes it.

Change-Id: Id204f09dfc674e71fb029ec08304c9d71a4d5579
Signed-off-by: Manojkiran Eda <manojkiran.eda@gmail.com>
diff --git a/README.md b/README.md
index c96d6fb..5c8a82e 100644
--- a/README.md
+++ b/README.md
@@ -111,8 +111,8 @@
     "displayname": "BIOS Serial Debug level",
     "description": "BIOS Serial Debug level during system boot.",
     "menuPath": "Advanced/Debug Feature Selection",
-    "current": 0x00,
-    "default": 0x01,
+    "current": "0x00",
+    "default": "0x01",
     "options": [
       { "optionstring": "MinBound", "optionvalue": 0 },
       { "optionstring": "MaxBound", "optionvalue": 4 },