Merge pull request #519 from LedgerHQ/tdj/update_client_readme

udpate the client README.md file

Author: tdejoigny-ledger

client/README.md

@@ -3,9 +3,17 @@
 This package allows to communicate with the Ledger Ethereum application, either on a
 real device, or emulated on Speculos.
 
-### Installation from sources
+## Installation from pypi.org
 
-You can install the client from this repo:
+You can install the client from `pypi.org`:
+
+  ```bash
+  pip install ledger_app_clients.ethereum
+  ```
+
+## Installation from sources
+
+You can also install the client from this repo:
 
 ```bash
 pip install .