docs: update example

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

Author: kgryte

lib/node_modules/@stdlib/number/float16/base/signbit/README.md

@@ -62,20 +62,16 @@ bool = signbit( -0.0 );
 
 ```javascript
 var toFloat16 = require( '@stdlib/number/float64/base/to-float16' );
-var randu = require( '@stdlib/random/base/randu' );
+var uniform = require( '@stdlib/random/array/uniform' );
+var map = require( '@stdlib/array/base/map' );
+var logEachMap = require( '@stdlib/console/log-each-map' );
 var signbit = require( '@stdlib/number/float16/base/signbit' );
 
-var sign;
-var x;
-var i;
+// Create an array of random half-precision floating-point numbers:
+var x = map( uniform( 100, -50.0, 50.0 ), toFloat16 );
 
-for ( i = 0; i < 100; i++ ) {
-    x = (randu()*100.0) - 50.0;
-    x = toFloat16( x );
-    sign = signbit( x );
-    sign = ( sign ) ? 'true' : 'false';
-    console.log( 'x: %d. signbit: %s.', x, sign );
-}
+// Determine whether the sign bit is on or off for each number:
+logEachMap( 'x: %0.4f => %s', x, signbit );
 ```
 
 </section>