Issue 3692 - Add base ESLint configuration

eslint-config-eyeo/README.md

+# eslint-config-eyeo
+
+An [ESLint](http://eslint.org) configuration that checks for compliance with the
+[Adblock Plus coding style guide](https://adblockplus.org/coding-style#javascript)
+which is used for all eyeo projects.
+
+## Installation
+
+    npm install -g eslint eslint-config-eyeo
+
+(As root, or using sudo.)
+
+## Usage
+
+To lint a JavaScript file using ESLint you simply run the `eslint` command with
+the file as an argument. For example:
+
+    eslint some-file.js
+
+(For advanced usage see `eslint --help`.)
+
+In order to use eslint-config-eyeo your project's ESLint configuration
+should extend from it. A minimal example looks like this:
+
+    {
+      "extends": "eslint-config-eyeo",
+      "root": true
+    }
+
+(For projects without an ESLint configuration you can create your own
+personal configuration in `~/.eslintrc.json`, but take care to remove
+the `"root": true` section from the above example.)