Raise the Node.js floor to match the driver it tells you to install

The Node.js quick start listed 'Node.js 18 or later' as its prerequisite
and then ran an unpinned 'npm install mongodb'. The current driver
requires Node >=20.19, so a reader on 18 satisfies the documented
prerequisite and then fails at install time with an engine error.

The same floor was corrected in documentdb/docs; this is the website-owned
copy of the same page.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: f18515db-c52f-4197-aa50-d81359c7c763
Signed-off-by: Guanzhou Song <guanzhou.song@gmail.com>

Author: GuanzhouSong

app/services/articleService.ts

@@ -537,7 +537,7 @@ Connect to DocumentDB from Node.js using the official MongoDB driver.
 
 ## Prerequisites
 
-- Node.js 18 or later
+- Node.js 20.19 or later (required by the current \`mongodb\` driver)
 - npm
 - [Docker](https://www.docker.com/)
 - Basic familiarity with JavaScript