Add readme w/ link to contributing instructions

Signed-off-by: Ryan Nett <[email protected]>

Author: rnett

tensorflow-core-kotlin/README.md

@@ -0,0 +1,8 @@
+# Kotlin API
+
+This is the home of the Kotlin API for TensorFlow Java.
+The API lives in `tensorflow-core-api`, and uses the annotation processor in `tensorflow-core-generator`.
+
+There is no framework wrapper yet, as most of the framework classes work fine from Kotlin, but if there is a need one could be addded.
+
+For contributing guidelines, see [CONTRIBUTING.md](../CONTRIBUTING.md#kotlin-api).