docs: add README information

README.md

@@ -1,3 +1,12 @@
+# @citation-js/plugin-enw
+
+Thie plugin adds support for [.enw files](https://en.wikipedia.org/wiki/EndNote#Import_format).
+
+[![NPM version](https://img.shields.io/npm/v/@citation-js/plugin-enw.svg)](https://npmjs.org/package/@citation-js/plugin-enw)
+[![Codecov](https://img.shields.io/codecov/c/gh/citation-js/plugin-enw)](https://app.codecov.io/gh/citation-js/plugin-enw)
+[![NPM total downloads](https://img.shields.io/npm/dt/@citation-js/plugin-enw.svg)](https://npmcharts.com/compare/@citation-js%2Fplugin-enw?minimal=true)
+![License](https://img.shields.io/npm/l/@citation-js/plugin-enw.svg)
+
 ## Install
 
 ```js
@@ -14,8 +23,50 @@ require('@citation-js/plugin-enw')
 
 ## Formats
 
-Formats and other features added by this plugin.
-
 ### Input
 
+**`@enw/file`**
+
+A text file in the `.enw` format.
+
+```js
+const data = Cite(`%0 Journal Article
+%A Willighagen, Lars G.
+%E Peroni, Silvio
+%P e214
+%V 5
+%J PeerJ Computer Science
+%T Citation.js: a format-independent, modular bibliography tool for the browser and command line
+%8 2019-08-12
+%R 10.7717/peerj-cs.214
+%@ 2376-5992
+%U https://peerj.com/articles/cs-214/
+`)
+
+data.format('data', { format: 'object' }) // returns:
+{
+  author: [{ family: 'Willighagen', given: 'Lars G.' }],
+  editor: [{ family: 'Peroni', given: 'Silvio' }],
+  page: 'e214',
+  volume: '5',
+  'container-title': 'PeerJ Computer Science',
+  title: 'Citation.js: a format-independent, modular bibliography tool for the browser and command line',
+  issued: { 'date-parts': [[2019, 8, 12]] },
+  type: 'article-journal',
+  DOI: '10.7717/peerj-cs.214',
+  ISSN: '2376-5992',
+  URL: 'https://peerj.com/articles/cs-214/
+}
+```
+
 ### Output
+
+**`enw`**
+
+```js
+data.format('enw', { format: 'text', lineEnding: '\n' })
+```
+
+Options:
+  - `format` (string): `'text'` (default; for plain text file) or `'object'` (for array of objects)
+  - `lineEnding` (string): e.g. `'\n'` (default) or `'\r\n'` (note that refer might not pick up on the latter)