feat(docs): prepare complete readme

README.md

@@ -4,18 +4,43 @@ Based on Blank boilerplate theme, this has been crafted for the personal website
 
 ![theme-preview](thumbnail.png)
 
-## Getting Started with Blank theme
+Contents:
 
-Work in progress...
+* [Getting Started](#getting-started)
+* [Usage](#usage)
+  * [Adding a portfolio image](#adding-a-portfolio-image)
+  * [Theme settings](#theme-settings)
+* [Acknowledgements](#acknowledgements)
+* [License](#license)
 
-## Acknowledgements
+## Getting Started
+
+1. Download **latest ZIP archive** from assets in [latest release](https://github.com/bigbrozer/publii-luci-theme/releases).
+2. Open Publii, [install or update the theme](https://getpublii.com/docs/installing-using-updating-themes.html#installingatheme) using the ZIP archive downloaded from previous step.
+3. In `Site settings`, select `Install and use ➔ Luci` to **install** or **update** the theme. Click `Save Settings` button to apply modification.
+4. See [Usage](#usage) for using and configuring the theme.
+
+## Usage
+
+Once the theme is installed, read following sections to know how to use and configure it.
+
+### Adding a portfolio image
 
-* Bob Mitro TidyCustoms ([@tidycustoms](http://twitter.com/tidycustoms) - [https://tidycustoms.net/](https://tidycustoms.net/))
+The portfolio (index page) is composed of posts with only a `title`, a `featured image` and ensure `Other options ➔ Post template ➔ Image for the portfolio` is set.
 
-## Documentation
+This combination will show the picture with a lightbox effect. The `title` is used as the image caption.
+
+### Theme settings
+
+From Publii, navigate to `Theme ➔ Custom settings` to customize the theme behavior.
+
+## Acknowledgements
 
-Work in progress...
+* [Lucie Besançon](https://me.labrume.art/) -- For all the GFX.
+* [Blank theme](https://github.com/GetPublii/theme-Blank) -- Blank is an empty, basic Publii theme for developers.
+* [UIKit](https://getuikit.com/) -- UIkit is a lightweight and modular front-end framework for developing fast and powerful web interfaces.
+* [Release It!](https://github.com/release-it/release-it) -- Generic CLI tool to automate versioning and package publishing-related tasks.
 
 ## License
 
-MIT
+See [LICENSE](./LICENSE).