docs: add installation instructions and screenshot of webapp (#50)

Author: jfdev001

docs/_static/lingua-loop.png

@@ -4,6 +4,66 @@ Welcome to lingua-loop's documentation!
 A web application to train your listening skills by transcribing real speech
 from YouTube videos.
 
+.. image:: _static/lingua-loop.png
+   :align: center
+
+Installation
+============
+
+You need Python version 3.12 or higher. It's recommended to create a dedicated
+virtual environment first.
+
+Using conda:
+
+.. code-block:: bash
+
+   conda create --name lingua-loop python=3.12
+   conda activate lingua-loop
+
+Using venv on Windows:
+
+.. code-block:: bat
+
+   python -m venv .venv_lingua_loop
+   .\.venv_lingua_loop\Scripts\activate
+
+Using venv on Linux/macOS:
+
+.. code-block:: bash
+
+   python -m venv .venv_lingua_loop
+   . .venv_lingua_loop/bin/activate
+
+Then install the package:
+
+.. code-block:: bash
+
+   pip install lingua-loop
+
+The package is also installable directly from the repository:
+
+.. code-block:: bash
+
+   pip install git+https://github.com/jfdev001/lingua-loop.git
+
+For a faster install using the ``uv`` package manager:
+
+.. code-block:: bash
+
+   uv pip install git+https://github.com/jfdev001/lingua-loop.git
+
+.. note::
+   This package is under active development and updated frequently.
+
+Usage
+=====
+
+Launch the app (which will open a web browser automatically):
+
+.. code-block:: bash
+
+   lingua-loop
+
 .. toctree::
    :maxdepth: 1
    :caption: Contents: