docs(pkg): readme file for add package (#498)

* docs(pkg): readme file for add package

* docs(add): fix missing content

Author: ematipico

packages/add/README.md

@@ -0,0 +1,26 @@
+# webpack-cli add
+
+## Description
+
+This package contains the logic to add new properties to the a webpack configuration file. It will run a generator that prompts the user for questions of which property to add to their webpack configuration file.
+
+## Installation
+
+```bash
+npm i -D webpack-cli @webpack-cli/add
+```
+
+## Usage
+
+To run the scaffolding instance programmatically, install it as a dependency. When using the package programmatically, one does not have to install webpack-cli.
+
+### Node
+```js
+const add = require("@webpack-cli/add");
+add();
+```
+
+### CLI (via `webpack-cli`)
+```bash
+npx webpack-cli add
+```