add build instruction and description

Author: LoSk-p

README.md

@@ -1,7 +1,40 @@
 # Libelium Calibration App
 
-## Run
+The Libelium Calibration App can be used for Libelium [Smart Water Sensors Kit](https://development.libelium.com/smart_water_sensor_guide) and [Smart Water ions Sensors kit](https://development.libelium.com/smart-water-ions-sensor-guide). App will work only with the [firmware](firmware) from this repository.
+
+The Libelium Calibration App allows to see the current measurements and calibrate sensors.
+
+The Libelium Calibration App is designed to be compatible with both the [Smart Water Sensors Kit](https://development.libelium.com/smart_water_sensor_guide) and the [Smart Water ions Sensors kit](https://development.libelium.com/smart-water-ions-sensor-guide) from Libelium. It is essential to note that the app is exclusively compatible with the [firmware](firmware) provided within this repository.
+
+This application enables users to view real-time measurements and conduct sensor calibration effortlessly.
+
+The latest executable files can be found in the latest release.
+
+## Build from source
+To build the application, Python version no older than 3.9 is required!
+
+Clone the repo:
+```bash
+git clone https://github.com/Multi-Agent-io/libelium-calibration-app.git
+cd libelium-calibration-app
+```
+Install dependencies:
+```bash
+pip3 install requirements.txt
+```
+Build GUI files:
+```bash
+pyuic5 app/gui/mainwindow.ui -o app/gui/mainwindow.py
+```
+And build executables:
+```bash
+pyinstaller app/main.py --onefile --windowed --name SmartWaterGUI
+```
+Executables will be in the `dist` folder.
+
+## Run Python Script
 ```bash
+pip3 install -r requirements.txt
 pyuic5 app/gui/mainwindow.ui -o app/gui/mainwindow.py
 python3 app/main.py
 ```