Add note about ESLint compatibility

Fixes #59

readme.md

@@ -15,9 +15,11 @@
 ## Install
 
 ```sh
-npm install --save-dev eslint-formatter-pretty
+npm install --save-dev eslint-formatter-pretty@5
 ```
 
+*To use this with ESLint, use version 5. Version 6 is [not compatible with ESLint](https://github.com/eslint/eslint/issues/15560).*
+
 ## Usage
 
 ### [XO](https://github.com/xojs/xo)
@@ -49,10 +51,10 @@ grunt.registerTask('default', ['eslint']);
 ### [gulp-eslint](https://github.com/adametry/gulp-eslint)
 
 ```js
-const gulp = require('gulp');
-const eslint = require('gulp-eslint');
+import gulp from 'gulp';
+import eslint from 'gulp-eslint';
 
-gulp.task('lint', () =>
+export const lint = (
  gulp.src('file.js')
  .pipe(eslint())
  .pipe(eslint.format('pretty'))
@@ -62,7 +64,9 @@ gulp.task('lint', () =>
 ### [eslint-loader](https://github.com/MoOx/eslint-loader) *(webpack)*
 
 ```js
-module.exports = {
+import eslintFormatterPretty from 'eslint-formatter-pretty';
+
+export default {
  entry: ['file.js'],
  module: {
  rules: [
@@ -71,7 +75,7 @@ module.exports = {
  exclude: /node_modules/,
  loader: 'eslint-loader',
  options: {
- formatter: require('eslint-formatter-pretty')
+ formatter: eslintFormatterPretty
  }
  }
  ]