Update README to include build instructions

README.md

@@ -1,4 +1,13 @@
 # IFPass
 
-IFPass is a python project developped for the "Institut Français en Hongrie" and published under MIT license.  
+IFPass is a python project developped for the "Institut Français en Hongrie" and published under [MIT license](https://framagit.org/SecT0uch/IFPass/blob/master/LICENSE).  
 It allows to manage a subscriber database and print member cards.
+
+## Build
+
+1. Install [NSIS](http://nsis.sourceforge.net/Download).
+2. Install python 3 and pip.
+3. Install the modules with `sudo -H pip install pynsist PyPDF2 termcolor`
+4. If pynsist version < 2.4, replace `/usr/lib/python3.*/site-packages/nsist/__init__.py` with https://raw.githubusercontent.com/takluyver/pynsist/master/nsist/__init__.py
+5. Run `./build.sh`
+