docs: update example

Signed-off-by: Athan <kgryte@gmail.com>

Author: kgryte

lib/node_modules/@stdlib/ndarray/any-by/README.md

@@ -202,6 +202,7 @@ var opts = {
 
 // Perform reduction:
 var out = anyBy.assign( x, y, opts, predicate );
+// returns <ndarray>[ true, false ]
 
 var bool = ( out === y );
 // returns true