remove root Makefile and get rid of cd in drone ci

docs/Makefile

@@ -0,0 +1,11 @@
+
+.PHONY: docs-copy
+docs-copy:
+	mkdir -p hugo/content/; \
+	cd hugo; \
+	git init; \
+	git remote rm origin; \
+	git remote add origin https://github.com/owncloud/owncloud.github.io; \
+	git fetch --depth=1; \
+	git checkout origin/source -f; \
+	rsync -ax --delete --exclude hugo/ --exclude Makefile ../. content/; \