fix grammar in verbatimModuleSyntax: "an ES modules" (#3382)

Author: NotWearingPants

packages/tsconfig-reference/copy/en/options/verbatimModuleSyntax.md

@@ -140,7 +140,7 @@ module.exports = {
 
 While this is a limitation, it does help make some issues more obvious.
 For example, it's very common to forget to set the [`type` field in `package.json`](https://nodejs.org/api/packages.html#type) under `--module node16`.
-As a result, developers would start writing CommonJS modules instead of an ES modules without realizing it, giving surprising lookup rules and JavaScript output.
+As a result, developers would start writing CommonJS modules instead of ES modules without realizing it, giving surprising lookup rules and JavaScript output.
 This new flag ensures that you're intentional about the file type you're using because the syntax is intentionally different.
 
 Because `--verbatimModuleSyntax` provides a more consistent story than `--importsNotUsedAsValues` and `--preserveValueImports`, those two existing flags are being deprecated in its favor.