doc: update Buffer(size) documentation

It returns zero-filled memory since v8.0.0.

PR-URL: #33198
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>

Author: seishun

doc/api/buffer.md

@@ -2521,9 +2521,7 @@ changes:
 * `size` {integer} The desired length of the new `Buffer`.
 
 See [`Buffer.alloc()`][] and [`Buffer.allocUnsafe()`][]. This variant of the
-constructor is equivalent to [`Buffer.allocUnsafe()`][], although using
-[`Buffer.alloc()`][] is recommended in code paths that are not critical to
-performance.
+constructor is equivalent to [`Buffer.alloc()`][].
 
 ### `new Buffer(string[, encoding])`
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