docs: add horizontal rule

Author: kgryte

lib/node_modules/@stdlib/ndarray/fancy/README.md

@@ -644,6 +644,8 @@ The method does **not** serialize data outside of the buffer region defined by t
 
 <!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
 
+* * *
+
 <section class="notes">
 
 ## Notes