docs: installation option via OpenUPM

README.md

@@ -4,11 +4,13 @@
 ## Dependency Injection Framework for Unity3D upm package
 
 [![Join the chat at https://gitter.im/Zenject/Lobby](https://badges.gitter.im/Zenject/Lobby.svg)](https://gitter.im/Zenject/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![openupm](https://img.shields.io/npm/v/zenject?label=openupm&registry_uri=https://package.openupm.com)](https://openupm.com/packages/zenject/)
 
 If you are looking for the older documentation for Zenject you can find that here:  <a href="https://github.com/modesttree/Zenject/tree/f0dd30ad451dcbc3eb17e636455a6c89b14ad537">Zenject 3.x</a>, <a href="https://github.com/modesttree/Zenject/tree/0b4a15b1e6e680c94fd34a2d7420eb41e320b21b">Zenject 4.x</a>, <a href="https://github.com/modesttree/Zenject/tree/dc019e31dbae09eb53c1638be00f7f002898956c">Zenject 5.x</a>
 
 ## Using
- For start using this package add lines into `./Packages/manifest.json` like next sample:  
+
+For start using this package add lines into `./Packages/manifest.json` like next sample:  
 ```json
 {
   "dependencies": {
@@ -17,6 +19,12 @@ If you are looking for the older documentation for Zenject you can find that her
 }
 ```
 
+Or install via the [OpenUPM registry](https://openupm.com), using [openupm-cli](https://github.com/openupm/openupm-cli).
+
+```
+openupm add zenject
+```
+
 ## <a id="introduction"></a>Introduction
 
 Zenject is a lightweight highly performant dependency injection framework built specifically to target Unity 3D (however it can be used outside of Unity as well).  It can be used to turn your application into a collection of loosely-coupled parts with highly segmented responsibilities.  Zenject can then glue the parts together in many different configurations to allow you to easily write, re-use, refactor and test your code in a scalable and extremely flexible way.