Update .editorconfig and fix conf indents (#8442)

.editorconfig

@@ -8,3 +8,7 @@ end_of_line = lf
 charset = utf-8
 trim_trailing_whitespace = true
 insert_final_newline = true
+
+[*.html]
+indent_style = tab
+indent_size = 4

docs/docusaurus.config.js

@@ -1,4 +1,3 @@
-/* eslint-disable import/no-commonjs */
 // VERSION replaced by deploy script
 module.exports = {
   title: 'Chart.js',

rollup.config.js

@@ -1,6 +1,3 @@
-/* eslint-disable import/no-commonjs */
-/* eslint-env es6 */
-
 const cleanup = require('rollup-plugin-cleanup');
 const dts = require('rollup-plugin-dts').default;
 const json = require('@rollup/plugin-json');