Add Module.md and document packages.

libraries/stdlib/src/Module.md

@@ -0,0 +1,22 @@
+Kotlin standard library is a set of functions and types implementing idiomatic patterns when working with collections,
+text and files.
+
+$kotlin: Core functions and types, available on all supported platforms,
+
+$kotlin.browser: API to access the web browser DOM
+
+$kotlin.concurrent: Concurrent programing API
+
+$kotlin.dom: Functions for working with the W3C DOM
+
+$kotlin.io: IO API for working with files and streams
+
+$kotlin.math: Mathematics API
+
+$kotlin.modules: API for defining compilation units
+
+$kotlin.template: Text processing API
+
+$kotlin.test: Functions for writing tests
+
+$kotlin.util: Utility functions