doc: update README with api docs info

Author: simonrw

README.md

@@ -18,6 +18,4 @@ kubectl apply -f https://github.com/localstack/localstack-operator-public/releas
 
 ## CRD definition
 
-The operator includes a `LocalStack` CRD which defines your LocalStack instance.
-
-Details TBD
+The operator includes a `LocalStack` CRD which defines your LocalStack instance. See the [./api-docs.md] for a description of the available fields.