pamhyr: Update README.

README.md

-# PamHyr (Programme d’Aide à la Modélisation en Hydraulique des Rivières)
+# Pamhyr2
+
+Pamhyr is a free and open source graphical user interface for 1D hydro-sedimentary
+modelling of rivers.
+
+## Features
+
++ Edit a complex river hydraulics network
++ Define the river geometry
++ Define boundary conditions
++ Define lateral contribution
++ Edit river friction
++ Generate initial conditions
++ Edit river sedimentary layers
++ Save the study in a unique file
++ Run Mage 8 on a study and visualize results
+
+## Install
+
+### GNU/Linux
+
+Downloads [last
+realease](https://gitlab.irstea.fr/theophile.terraz/pamhyr/-/releases/permalink/latest)
+GNU/Linux binary archive.
+
+```shell
+tar xf pamhyr-gnulinux-amd64.tar.xz
+cd pamhyr
+./pamhyr
+```
+
+### Windows
+
+Downloads [last
+realease](https://gitlab.irstea.fr/theophile.terraz/pamhyr/-/releases/permalink/latest)
+Windows installer.
+
+### From source code
+
+```shell
+# Get source code
+git clone https://gitlab.irstea.fr/theophile.terraz/pamhyr/
+cd pamhyr
+
+# Install dependencies
+pip3 install -r requirements.txt
+
+# Run pamhyr
+./src/pamhyr.py
+
+```