chore(README): update docs

Author: haruspeks

README.md

@@ -2,15 +2,32 @@
 
 Avoc is a GEOINT tool which combines multiple map providers and view modes in one single interface, and equipped with a series of companion tools for scraping geotagged/georeferenced contents.
 
-# Under the hood
+## Setup
+
+### From Github
+1. Clone the repo
+2. Copy the file `configuration.js.sample` into `configuration.js`
+3. Open `configuration.js` and add a valid Google Maps' API key to apiKeys.google
+
+### Manually
+1. Download the latest release [available here](https://github.com/haruspeks/avoc/releases)
+2. Open `configuration.js` and add a valid Google Maps' API key to apiKeys.google
+
+### How to obtain a Google Maps API key
+A good how-to guide is [available here](https://dev.to/simplecodeagency/how-to-setup-a-new-google-maps-api-key-4kp1).
+
+## Under the hood
 
 - [Pico.css](https://picocss.com/)
 - [Alpine.js](https://alpinejs.dev/)
+- [RequireJS](https://requirejs.org/)
+- Weather data powered by [OpenMeteo](https://open-meteo.com/)
+- Altitude data powered by [OpenMeteo](https://open-meteo.com/) and [Open-Elevation](https://www.open-elevation.com/)
 
-# Browser compatibility
+## Browser compatibility
 
 Edge 16+, Firefox 52+, Safari 10+, Chrome 57+, Opera 44+.
 
-# Credits
+## Credits
 
 `kiwi-bird` favicon by [Free Icons](https://free-icons.github.io/free-icons/).