Update README

README.md

@@ -3,4 +3,21 @@
 Cesium 2, running on Substrate
 
 
+# Build
+
+## In a post-it
+
+```bash
+
+# Get sources
+git clone git@git.duniter.org:clients/cesium-grp/cesium2s.git
+cd cesium2s
+
+# Install NodeJS v14+, then deps
+nvm use 14
 npm install -g yarn @ionic/cli @angular/cli
+npm install
+
+# Build and run !
+npm run start
+```