doc: add license info to the README

PR-URL: https://github.com/nodejs/node/pull/36278
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

README.md

@@ -34,6 +34,7 @@ The Node.js project uses an [open governance model](./GOVERNANCE.md). The
   * [TSC (Technical Steering Committee)](#tsc-technical-steering-committee)
   * [Collaborators](#collaborators)
   * [Release Keys](#release-keys)
+* [License](#license)
 
 ## Support
 
@@ -645,6 +646,14 @@ Other keys used to sign some previous releases:
 * **Timothy J Fontaine** <tjfontaine@gmail.com>
 `7937DFD2AB06298B2293C3187D33FF9D0246406D`
 
+## License
+
+Node.js is available under the
+[MIT license](https://opensource.org/licenses/MIT). Node.js also includes
+external libraries that are available under a variety of licenses.  See
+[LICENSE](https://github.com/nodejs/node/blob/master/LICENSE) for the full
+license text.
+
 [Code of Conduct]: https://github.com/nodejs/admin/blob/master/CODE_OF_CONDUCT.md
 [Contributing to the project]: CONTRIBUTING.md
 [Node.js Website]: https://nodejs.org/