Document node version, fix #1444

Author: michielbdejong

README.md

@@ -133,6 +133,7 @@ also add to `config.json`
 ```
 
 ### Upgrading from version <5.3
+Make sure you're running Node version 10 or later.
 Please take into account the [v5.3 upgrade notes](https://github.com/solid/node-solid-server/blob/master/CHANGELOG.md#530-upgrade-notes).
 
 ### Upgrading from version <5.0