Update README.md deprecating legacy REST

Change-Id: If9cc1d9459c5fb06ebfc260dfe80b2bc35f0fe1e
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/README.md b/README.md
index 429b143..a0f9a91 100644
--- a/README.md
+++ b/README.md
@@ -100,7 +100,8 @@
 classified as follows:
 
 `tests/`: Contains the general test cases for OpenBMC stack functional
-          verification.
+          verification. The "tests" subdirectory uses legacy REST and will be
+          deprecated at some point and therefore no longer supported.
 
 `extended/`: Contains test cases for boot testing, network testing,
              code update testing etc.