docs: add same value example

Ref: #1339
Ref: 634044b

Author: kgryte

lib/node_modules/@stdlib/array/base/count-same-value/README.md

@@ -51,6 +51,15 @@ var out = countSameValue( x, 1 );
 // returns 2
 ```
 
+In contrast to an implementation using the strict equality operator `===`, the function distinguishes between `+0` and `-0` and treats `NaNs` as the same value.
+
+```javascript
+var x = [ NaN, NaN, NaN ];
+
+var out = countSameValue( x, NaN );
+// returns 3
+```
+
 </section>
 
 <!-- /.usage -->