Update README

Author: ehmicky

README.md

@@ -73,6 +73,10 @@ npm install -D log-process-errors
 This is because logging is modified globally and libraries users might not
 expect this side-effect. Also, this might lead to conflicts between libraries.
 
+This package is an ES module and must be loaded using
+[an `import` or `import()` statement](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c),
+not `require()`.
+
 # Usage
 
 ```js