Add scaladoc links

Author: gzm0

README.md

@@ -2,3 +2,9 @@
 
 `scalajs-js-envs` is a generic API for JVM processes to spawn and communicate with JavaScript environments.
 It is used by Scala.js integrations in build tools to run and test Scala.js libraries and applications, but it is not specific to Scala.js-generated binaries.
+
+## Scaladoc
+
+*   [scalajs-js-envs](https://javadoc.io/doc/org.scala-js/scalajs-js-envs_2.13/latest/org/scalajs/jsenv/index.html)
+*   [scalajs-js-envs-test-kit](https://javadoc.io/doc/org.scala-js/scalajs-js-envs-test-kit_2.13/latest/org/scalajs/jsenv/test/index.html)
+*   [scalajs-env-nodejs](https://javadoc.io/doc/org.scala-js/scalajs-env-nodejs_2.13/latest/org/scalajs/jsenv/nodejs/index.html)