Add Node.js version support to readme

Author: jsumners

README.md

@@ -43,6 +43,25 @@ client on your system:
 
     npm install ldapjs
 
+## Node.js Version Support
+
+As of `ldapjs@3` we only support the active Node.js LTS releases.
+See [https://github.com/nodejs/release#release-schedule][schedule] for the LTS
+release schedule.
+
+For a definitive list of Node.js version we support, see the version matrix
+we test against in our [CI configuration][ci-config].
+
+Note: given the release date of `ldapjs@3`, and the short window of time that
+Node.js v14 had remaining on its LTS window, we opted to not support Node.js
+v14 with `ldapjs@3` (we released late February 2023 and v14 goes into
+maintenance in late April 2023). Also, Node.js v14 will be end-of-life (EOL) on
+September 11, 2023; this is a very shortened EOL timeline and makes it even
+more reasonable to not support it at this point.
+
+[schedule]: https://github.com/nodejs/release#release-schedule
+[ci-config]: https://github.com/ldapjs/node-ldapjs/blob/master/.github/workflows/main.yml
+
 ## License
 
 MIT.