add documentation for recently added packages

libraries/stdlib/src/Module.md

@@ -21,6 +21,10 @@ Utility functions for concurrent programming.
 
 Functions for working with the W3C DOM.
 
+# Package kotlin.jvm
+
+Functions and annotations specific to the Java platform.
+
 # Package kotlin.io
 
 IO API for working with files and streams.
@@ -33,10 +37,29 @@ Mathematics API.
 
 API for defining compilation units.
 
+# Package kotlin.platform
+
+APIs for customizing the code generated by the Kotlin compiler for better interoperability with
+other code on the target platform.
+
+# Package kotlin.properties
+
+Standard implementations of delegates for [delegated properties](/docs/reference/delegated-properties.html)
+and helper functions for implementing custom delegates.
+
+# Package kotlin.reflect
+
+Runtime API for [Kotlin reflection](/docs/reference/reflection.html)
+
+# Package kotlin.reflect.jvm
+
+Runtime API for interoperability between [Kotlin reflection](/docs/reference/reflection.html) and
+Java reflection.
+
 # Package kotlin.test
 
-Functions for writing tests
+Functions for writing tests.
 
 # Package kotlin.util
 
-Utility functions
+Utility functions.