docs: add Raspberry Pi setup guide and update installation instructions

Signed-off-by: Dominik Willner <th33xitus@gmail.com>

docs/setup/installation.md

@@ -0,0 +1,39 @@
+# Installing KIAUH
+
+In the following sections, you will be guided through the installation
+process step-by-step.
+
+To use KIAUH, it is enough to download the script and run it on your
+Raspberry Pi or other compatible device. If you need to know how to
+set up a Raspberry Pi or if you are unsure whether your current setup
+is sufficient, please refer to the [Raspberry Pi Installation Guide](raspberry-pi-setup.md)
+and follow the steps therein. Afterwards, you can return to this guide to install KIAUH.
+
+### Prerequisites
+Before you can download and run KIAUH, you need to ensure that ``git`` is
+installed on your system. Open a terminal and run the following command:
+
+```bash
+sudo apt-get update && sudo apt-get install git -y
+```
+
+### Downloading KIAUH
+After `git` was successfully installed, you can download KIAUH by
+cloning the repository from GitHub. It is recommended to clone it into
+your home directory. Run the following command in your terminal:
+```bash
+cd ~ && git clone https://github.com/dw-0/kiauh.git
+```
+
+### Running KIAUH
+Once the repository is cloned, you can start KIAUH. Make sure you are in
+your home directory and execute the script by running the following
+command:
+```bash
+./kiauh/kiauh.sh
+```
+
+After executing the command, you will be presented with the KIAUH menu,
+which allows you to install and manage various 3D printing software.
+For more information on how to use KIAUH, please refer to the
+[Usage Guide](usage.md).