cherrypick from master - add overview description for RS API reference Change-Id: Id5554c607ad4c435f92bfa939e4ce4833a638f62

Change-Id: Iff4b4bd171818208bb3be46dd3ef7e91b6cbd80f

Author: Robert Ly

libs/rs/scriptc/rs_allocation.rsh

@@ -14,6 +14,31 @@
  * limitations under the License.
  */
 
+/*! \mainpage notitle
+ *
+ * Renderscript is a high-performance runtime that provides graphics rendering and
+ * compute operations at the native level. Renderscript code is compiled on devices
+ * at runtime to allow platform-independence as well.
+ * This reference documentation describes the Renderscript runtime APIs, which you
+ * can utilize to write Renderscript code in C99. The Renderscript header
+ * files are automatically included for you, except for the rs_graphics.rsh header. If
+ * you are doing graphics rendering, include the graphics header file like this:
+ *
+ * <code>#include "rs_graphics.rsh"</code>
+ *
+ * To use Renderscript, you need to utilize the Renderscript runtime APIs documented here
+ * as well as the Android framework APIs for Renderscript.
+ * For documentation on the Android framework APIs, see the <a href=
+ * "http://developer.android.com/reference/android/renderscript/package-summary.html">
+ * android.renderscript</a> package reference.
+ * For more information on how to develop with Renderscript and how the runtime and
+ * Android framework APIs interact, see the <a href=
+ * "http://developer.android.com/guide/topics/renderscript/index.html">Renderscript
+ * developer guide</a> and the <a href=
+ * "http://developer.android.com/resources/samples/RenderScript/index.html">
+ * Renderscript samples</a>.
+ */
+
 /** @file rs_allocation.rsh
  *  \brief Allocation routines
  *