Update readme

* Know Issues
  * kaniko in non-official images
  * v1 Registry Schema

README.md

@@ -87,7 +87,10 @@ After each command, we append a layer of changed files to the base image (if the
 
 ## Known Issues
 
-kaniko does not support building Windows containers.
+* kaniko does not support building Windows containers.
+* Running kaniko in any Docker image other than the official kaniko image is not supported (ie YMMV).
+  * This includes copying the kaniko executables from the official image into another image.
+* kaniko does not support the v1 Registry API ([Registry v1 API Deprecation](https://engineering.docker.com/2019/03/registry-v1-api-deprecation/))
 
 ## Demo