docs: Adding API level 27 (Oreo MR1) to the docs build options

We also need to modify the server settings to add the watermark to
docs with API level 27.

Test: make ds-docs
Bug: 67459392
Change-Id: I7c0f74924a5b39dede4c324069ff05e26eec5413
diff --git a/Android.mk b/Android.mk
index 77a4d83..dfcfa2b 100644
--- a/Android.mk
+++ b/Android.mk
@@ -1017,6 +1017,7 @@
     -since $(SRC_API_DIR)/24.txt 24 \
     -since $(SRC_API_DIR)/25.txt 25 \
     -since $(SRC_API_DIR)/26.txt 26 \
+    -since $(SRC_API_DIR)/27.txt 27 \
     -werror -lerror -hide 111 -hide 113 -hide 121 -hide 125 -hide 126 -hide 127 -hide 128 \
     -overview $(LOCAL_PATH)/core/java/overview.html \