chore: doc for npm usage

README.md

@@ -6,7 +6,7 @@ Markdown service in atom-ide-community packages (e.g. ide-datatip).
 
 Just install.
 
-### Developer Usage
+### Developer Usage - As apm package
 
 Put this in your `package.json`
 
@@ -41,3 +41,30 @@ export function consumeMarkdownRenderer(markdownService: MarkdownService) {
 ```js
 let renderer: (markdownText: string, grammar: string) => Promise<string>
 ```
+
+### Developer Usage - as npm package - ES6 modules
+```
+npm install --save atom-ide-markdown-service
+```
+
+and use it inside your package like this:
+
+```js
+import { render as renderer } from "atom-ide-markdown-service/lib/renderer"
+```
+
+in which renderer is a function with this type `renderer(markdownText: string, grammar: string) => Promise<string>`
+
+### Developer Usage - as npm package - commonjs
+```
+npm install --save atom-ide-markdown-service
+```
+
+and use it inside your package like this:
+
+```js
+const { provideMarkdownRenderer } = require("atom-ide-markdown-service")
+const { render } = provideMarkdownRenderer()
+```
+
+in which render is a function with this type `renderer(markdownText: string, grammar: string) => Promise<string>`