Update TESTING.asciidoc with platform specific instructions
This adds the instructions for building a platform-specific distribution.
@@ -16,6 +16,15 @@ following:
./gradlew assemble
-----------------------------
+To create a platform-specific build including the x-pack modules, use the
+following depending on your operating system:
+
+-----------------------------
+./gradlew :distribution:archives:linux-tar:assemble --parallel
+./gradlew :distribution:archives:darwin-tar:assemble --parallel
+./gradlew :distribution:archives:windows-zip:assemble --parallel
+-----------------------------
+
=== Running Elasticsearch from a checkout
In order to run Elasticsearch from source without building a package, you can
