Indicate differences with upstream in the README.

README.md

@@ -5,6 +5,22 @@ Copanier is a minimalist grouped-command management software.
 It helps people to order a set of defined products, and provide a few helpers
 to ease the life of everyone involved :-)
 
+## Fork
+
+This project is a modified version [of the project started by Yohan](https://framagit.org/ybon/copanier).
+
+The main differences are :
+
+- Support for multiple producers (and persons to handle these producers)
+- A concept of groups was added : multiple persons can belong to the same group (and create / edit orders).
+- A minimal interface to add  / remove / update products from the website.
+- Support for out of stock products.
+- Automatically compute a settlement plan (using the [debts library](https://framagit.org/almet/debts))
+- A special page with tools to ease delivery management
+- Drop support for CSV files
+- Send emails to producers referents, with an order summary
+- Generation of PDF files rather than XLS files (for order summary, signing sheet and paiements repartition)
+
 ## Philosophy
 
 - Keep things simple
@@ -28,7 +44,7 @@ rest of the system:
 
 ```bash
 $ # Get the source code locally
-$ git clone https://framagit.org/ybon/copanier.git
+$ git clone https://framagit.org/almet/copanier.git
 $ cd copanier
 
 $ # Create the virtualenv