(minor change) Update readme with build instructions

readme.md

@@ -7,18 +7,46 @@ It also allows a javascript to connect to a Satochip from the browser as in the
 ## Requirements
 
 Python dependencies can be installed with:
-    ```
+
     $ python3 -m pip install -r requirements.txt
-    ```
+
 
 ## Run from sources
+
+    $ python3 satochip_bridge/Satochip-bridge.py
+
+
+## Build the Linux binaries
+
+This assumes an Ubuntu host, but it should not be too hard to adapt to another
+similar system. The host architecture should be x86_64 (amd64).
+The docker commands should be executed in the project's root folder.
+
+The script is based on [Electrum building script](https://github.com/spesmilo/electrum/tree/master/contrib/build-linux/appimage)
+
+1. Install Docker
 
     ```
-    $ python3 Satochip-bridge.py
+    $ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
+    $ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
+    $ sudo apt-get update
+    $ sudo apt-get install -y docker-ce
     ```
 
-## Build the binaries
-
-to do.
+2. Build docker image
+    ```
+	$ sudo docker build -t satochip-bridge-appimage-builder-img contrib/build-linux/appimage
+    ```
 
+3. Build AppImage
+    ```
+	$ sudo docker run -it \
+		--name satochip-bridge-appimage-builder-cont \
+		-v $PWD:/opt/satochip_bridge \
+		--rm \
+		--workdir /opt/satochip_bridge/contrib/build-linux/appimage \
+		satochip-bridge-appimage-builder-img \
+		./build.sh
+    ```
 
+4. The generated binary is in `./dist`.