feat: adding the value of pi-squared for float16

Author: DivyanshuVortex

lib/node_modules/@stdlib/constants/float16/pi-squared/README.md

@@ -128,6 +128,8 @@ Macro for the square of the mathematical constant [π][@stdlib/constants/float16
 
 <section class="links">
 
+[@stdlib/constants/float16/pi]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/constants/float16/pi
+
 </section>
 
 <!-- /.links -->