Installation.md

@@ -37,6 +37,13 @@ git clone https://framagit.org/espace-dev/sen2chain.git
 cd sen2chain
 pip3 install --user -e .
 ```
+## Updating sen2chain
+Go to the install directory, pull last updates from Framagit, and if necessary reinstall Sen2Chain (to get new requirement libraries). 
+```
+cd sen2chain
+git pull
+pip3 install --user -e .
+```
 
 ## Configuration