docs: add preview sdk docs to provide an api overview and install steps,
enable the 'preview' flag for the docs build
revise sdk side nav for preview

Change-Id: Ifc26cfb1f18e394e96853fd42f0e194d5f8552f3
diff --git a/Android.mk b/Android.mk
index 4c135da..0fe1164 100644
--- a/Android.mk
+++ b/Android.mk
@@ -449,12 +449,12 @@
 framework_docs_SDK_VERSION:=2.3
   # release version (ie "Release x")  (full releases only)
 framework_docs_SDK_REL_ID:=1
-  # flag to build offline docs for a preview release
-framework_docs_SDK_PREVIEW:=0
 
 framework_docs_LOCAL_DROIDDOC_OPTIONS += \
 		-hdf sdk.version $(framework_docs_SDK_VERSION) \
-		-hdf sdk.rel.id $(framework_docs_SDK_REL_ID)
+		-hdf sdk.rel.id $(framework_docs_SDK_REL_ID) \
+		-hdf sdk.preview true \
+		-hdf sdk.preview.version Honeycomb
 
 # ====  the api stubs and current.xml ===========================
 include $(CLEAR_VARS)
@@ -540,9 +540,6 @@
 		-sdkvalues $(OUT_DOCS) \
 		-hdf android.whichdoc offline
 
-ifeq ($(framework_docs_SDK_PREVIEW),true)
-  LOCAL_DROIDDOC_OPTIONS += -hdf sdk.preview true
-endif
 
 LOCAL_DROIDDOC_CUSTOM_TEMPLATE_DIR:=build/tools/droiddoc/templates-sdk