Added README.md for the utils directory

doc.zih.tu-dresden.de/util/README.md

+# Check scripts
+
+## check-no-floating.sh
+
+This script contains to checks.
+It first checks the hierarchy depth of the file structure and
+the second check tests if every markdown file is included in the navigation.
+
+### Usage
+
+```bash
+./doc.zih.tu-dresden.de/utils/check-no-floating.sh doc.zih.tu-dresden.de
+```
+
+### Return codes
+
+   * -1/255 if any error occure