Update docs for UnifiedPush 2.0 spec

Makefile

@@ -149,6 +149,14 @@ release-check-tags:
 	 	echo "ERROR: Must update docs/install.md with latest tag first.";\
 	 	exit 1;\
 	fi
+	if grep -q XXXXX docs/releases.md; then\
+		echo "ERROR: Must update docs/releases.md, found XXXXX.";\
+		exit 1;\
+	fi
+	if ! grep -q $(LATEST_TAG) docs/releases.md; then\
+		echo "ERROR: Must update docs/releases.mdwith latest tag first.";\
+		exit 1;\
+	fi
 
 release: build-deps release-check-tags check
 	goreleaser release --rm-dist --debug