docs: update return annotation

Signed-off-by: Athan <[email protected]>

Author: kgryte

lib/node_modules/@stdlib/stats/base/dsmean/README.md

@@ -61,7 +61,7 @@ var Float32Array = require( '@stdlib/array/float32' );
 var x = new Float32Array( [ 1.0, -2.0, 2.0 ] );
 
 var v = dsmean( x.length, x, 1 );
-// returns ~0.333
+// returns ~0.33333
 ```
 
 The function has the following parameters: