Add back doc-comment-check-docs back to checkbuild.

Test: m -j checkbuild, and build was failed as expected.
Bug: b/118815658 b/120229228
Change-Id: I3a8e869f22e5040a63208169203feec15b847f2f
diff --git a/Android.mk b/Android.mk
index 770ec20..8fb7e4e 100644
--- a/Android.mk
+++ b/Android.mk
@@ -72,6 +72,11 @@
 	$(hide) mkdir -p $(OUT_DOCS)/offline-sdk
 	( unzip -qo $< -d $(OUT_DOCS)/offline-sdk && touch -f $@ ) || exit 1
 
+# Run this for checkbuild
+checkbuild: doc-comment-check-docs
+# Check comment when you are updating the API
+update-api: doc-comment-check-docs
+
 # ==== hiddenapi lists =======================================
 .KATI_RESTAT: \
 	$(INTERNAL_PLATFORM_HIDDENAPI_WHITELIST) \