add android page

docs/modules/sdk/nav.adoc

@@ -24,6 +24,7 @@
 ***  xref:application_deployment.adoc[Application Deployment]
 ****  xref:default_build_script.adoc[Default Build Script]
 ****  xref:android.adoc[Android]
+****  xref:android_cheat_sheet.adoc[Android Cheat Sheet]
 ****  xref:ios.adoc[iOS]
 ** Unique Features
 ***  xref:model_loader_and_viewer.adoc[Import, View, Convert Models]