tools: prepare tools/doc for to-vfile 8.0.0

toVFile.readSync() is removed in favor of readSync().

PR-URL: nodejs#48485
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>

Author: Trott

tools/doc/addon-verify.mjs

@@ -8,14 +8,14 @@ import { mkdir, writeFile } from 'fs/promises';
 
 import gfm from 'remark-gfm';
 import remarkParse from 'remark-parse';
-import { toVFile } from 'to-vfile';
+import { readSync } from 'to-vfile';
 import { unified } from 'unified';
 
 const rootDir = new URL('../../', import.meta.url);
 const doc = new URL('./doc/api/addons.md', rootDir);
 const verifyDir = new URL('./test/addons/', rootDir);
 
-const file = toVFile.readSync(doc, 'utf8');
+const file = readSync(doc, 'utf8');
 const tree = unified().use(remarkParse).use(gfm).parse(file);
 const addons = {};
 let id = 0;