doc: add node: prefix for examples

Core modules are currently distinguished with the `node:` prefix.
This updates a few examples in docs to use the prefix for consistency.

Signed-off-by: Daeyeon Jeong <daeyeon.dev@gmail.com>
PR-URL: #45328
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>

Author: daeyeon

doc/api/diagnostics_channel.md

@@ -164,15 +164,15 @@ will be run synchronously whenever a message is published to the channel. Any
 errors thrown in the message handler will trigger an [`'uncaughtException'`][].
 
 ```mjs
-import diagnostics_channel from 'diagnostics_channel';
+import diagnostics_channel from 'node:diagnostics_channel';
 
 diagnostics_channel.subscribe('my-channel', (message, name) => {
   // Received data
 });
 ```
 
 ```cjs
-const diagnostics_channel = require('diagnostics_channel');
+const diagnostics_channel = require('node:diagnostics_channel');
 
 diagnostics_channel.subscribe('my-channel', (message, name) => {
   // Received data
@@ -194,7 +194,7 @@ Remove a message handler previously registered to this channel with
 [`diagnostics_channel.subscribe(name, onMessage)`][].
 
 ```mjs
-import diagnostics_channel from 'diagnostics_channel';
+import diagnostics_channel from 'node:diagnostics_channel';
 
 function onMessage(message, name) {
   // Received data
@@ -206,7 +206,7 @@ diagnostics_channel.unsubscribe('my-channel', onMessage);
 ```
 
 ```cjs
-const diagnostics_channel = require('diagnostics_channel');
+const diagnostics_channel = require('node:diagnostics_channel');
 
 function onMessage(message, name) {
   // Received data

doc/api/v8.md

@@ -919,17 +919,17 @@ contains the following script:
 ```cjs
 'use strict';
 
-const fs = require('fs');
-const zlib = require('zlib');
-const path = require('path');
-const assert = require('assert');
+const fs = require('node:fs');
+const zlib = require('node:zlib');
+const path = require('node:path');
+const assert = require('node:assert');
 
 const {
   isBuildingSnapshot,
   addSerializeCallback,
   addDeserializeCallback,
   setDeserializeMainFunction
-} = require('v8').startupSnapshot;
+} = require('node:v8').startupSnapshot;
 
 const filePath = path.resolve(__dirname, '../x1024.txt');
 const storage = {};

doc/api/webstreams.md

@@ -1476,8 +1476,8 @@ console.log(`from readable: ${data.byteLength}`);
 
 ```cjs
 const { arrayBuffer } = require('node:stream/consumers');
-const { Readable } = require('stream');
-const { TextEncoder } = require('util');
+const { Readable } = require('node:stream');
+const { TextEncoder } = require('node:util');
 
 const encoder = new TextEncoder();
 const dataArray = encoder.encode(['hello world from consumers!']);