Update README.md for new stable ver release

README.md

@@ -31,9 +31,7 @@ Currently, the supported tensor network libraries are:
 To get started:
  
 ```sh
-git clone https://github.com/qiboteam/qibotn.git
-cd qibotn
-poetry install
+pip install qibotn
 ```
  
 to install the tools and dependencies. A few extras are provided, check `pyproject.toml` in
@@ -41,6 +39,16 @@ case you need them.
  
 <!-- TODO: describe extras, after Poetry adoption and its groups -->
  
+## Contribute
+ 
+To contribute, please install using poetry:
+ 
+```sh
+git clone https://github.com/qiboteam/qibotn.git
+cd qibotn
+poetry install
+```
+
 ## Sample Codes
 
 ### Single-Node Example