evoling api note

Author: rahil-c

spec/README.md

@@ -20,6 +20,7 @@
 # Open API spec
 
 The `rest-service-open-api.yaml` defines the api contract for running table format conversion using XTable's REST service.
+This spec is still under active development and is subject to changes.
 
 ## Lint
 

spec/rest-service-open-api.yaml

@@ -22,7 +22,7 @@ info:
     url: https://www.apache.org/licenses/LICENSE-2.0.html
   version: 0.0.1
   description: |
-    A REST API for initiating metadata conversion using Apache XTable.
+    A REST API for initiating metadata conversion using Apache XTable. Note this spec is still under active development and is subject to changes.
 
 servers:
   - url: "{scheme}://{host}/{prefix}"