Add guidelines on how to add support for new devices to the README

Author: tsterbak

README.md

@@ -57,7 +57,26 @@ Start the desktop app and follow the instructions.
 2. Run `make poetry` and `make install` to setup poetry and the relevant requirements
 3. Clone this Run `make app` to start the desktop app from the source code.
 
-## Add your own installation configurations
+## Contribute your own installation configurations
+
+If you want to use the tool for a non-supported smartphone, the fastest way is to adapt an [existing config file](https://github.com/openandroidinstaller-dev/openandroidinstaller/tree/main/openandroidinstaller/assets/configs).
+
+Every step in the config file corresponds to one view in the application. These steps should contain the following fields:
+- `title`: str; Describing the overall goal of the step. Will be displayed in the header of the view.
+- `type`: str; Corresponds to the type of view to generate. There are the following options:
+  - `text`: Just display the text given in content.
+  - `confirm_button`: Display the content, as well as a button to allow the user to go to the next step.
+  - `call_button`: Display the content text and a button that runs a given command. After the command is run, a confirm button is displayed to allow the user to move to the next step.
+  - `call_button_with_input`: Display the content text, an input field and a button that runs a given command. The inputtext, can be used in the command by using the `<inputtext>` placeholder in the command field. After the command is run, a confirm button is displayed to allow the user to move to the next step.
+- `content`: str; The content text displayed alongside the action of the step. Used to inform the user about whats going on.
+- `command`: [ONLY for call_button* steps] str; This is a terminal command run in a shell. (For example fastboot or adb). There are three types of placeholders supported, that will be filled by the tool as soon as information is given.
+  - `<image>`: The path of the image file.
+  - `<recovery>`: The path of the recovery file.
+  - `<inputtext>`: Text from the user input from `call_button_with_input` views.
+- `allow_skip`: [OPTIONAL] boolean; If a skip button should be displayed to allow skipping this step. Can be useful when the bootloader is already unlocked.
+
+After you created a config file, you can open a pull request to make the file available to other users. The file should be named after device name output by `adb shell dumpsys bluetooth_manager | grep 'name:' | cut -c9-` when the devices is connected to the computer. Please also add the device to the supported devices table above.
+
 
 ## Contributing