Update modules.md

Co-authored-by: Geoffrey Booth <webadmin@geoffreybooth.com>

Author: mcollina

doc/api/modules.md

@@ -93,7 +93,26 @@ By default, Node.js will treat the following as CommonJS modules:
 * Files with an extension that is not `.mjs`, `.cjs`, `.json`, `.node`, or `.js`
   (when the nearest parent `package.json` file contains a top-level field
   [`"type"`][] with a value of `"module"`, those files will not be recognized as
-  CommonJS modules).
+By default, Node.js will treat the following as CommonJS modules:
+
+* Files with a `.cjs` extension.
+
+* Files with a `.js` extension or without an extension, when the nearest parent
+`package.json` file contains a top-level field [`"type"`][] with a value of
+`"commonjs"`.
+
+* Files with a `.js` extension or without an extension, when the nearest parent
+`package.json` file doesn't contain a top-level field [`"type"`][] or there is
+no `package.json` in any parent folder; unless the file contains syntax that
+errors unless it is evaluated as an ES module. Package authors should include
+the [`"type"`][] field, even in packages where all sources are CommonJS. Being
+explicit about the `type` of the package will make things easier for build
+tools and loaders to determine how the files in the package should be
+interpreted.
+
+* Files with an extension that is not `.mjs`, `.cjs`, `.json`, `.node`, or `.js`,
+when the nearest parent `package.json` file contains a top-level field
+[`"type"`][] with a value of `"module"`.
 
 See [Determining module system][] for more details.