doc: RPi Install Update

This commit significantly enhances the setup instructions specifically
for Raspberry Pi users in the README.md file. The updates aim to provide
clearer, more detailed, and step-by-step guidance for setting up the
project on Raspberry Pi environments, especially addressing issues
related to dependencies and configurations.

Key Changes:

1. **Added Pre-requisites Section**: Introduced a new section detailing
   the pre-requisites for setting up the project on Raspberry Pi. This
   includes using Raspberry Pi OS Bullseye for better compatibility and
   the necessary library installations for `opencv-python`.

2. **Updated Repository Prioritization**: Instructions have been
   provided to modify `pyproject.toml` to prioritize the piwheels
   repository over PyPI for more reliable and faster package
   installations specific to the Raspberry Pi.

3. **Cleaner Documentation Structure**: Organized the Raspberry Pi
   section into a more readable and step-by-step format, making it
   easier for users to follow and apply the instructions.

This update to the README.md ensures that users attempting to set up the
project on Raspberry Pi have all the necessary information at their
disposal, reducing setup issues and enhancing the overall user
experience on such devices.

Author: Mr. ChatGPT

README.md

@@ -39,16 +39,82 @@ The ability to develop, test and debug the launcher and facial recognition funct
    ```
 
    1. Raspberry Pi:
-      Most likely you will run into `KeyRing` errors when installing over ssh on raspberry pi.
 
-      To get around it:
+      1. Pre-requisites:
+         For faster and reliable install, use [Raspberry Pi OS Bullseye](https://downloads.raspberrypi.com/raspios_oldstable_armhf/images/raspios_oldstable_armhf-2023-12-06/2023-12-05-raspios-bullseye-armhf.img.xz).
+         Binary wheels packages are available for `opencv-python` only for Bullseye currently. See [pi wheels/opencv-python wheel](https://www.piwheels.org/project/opencv-python/)
+         Install the pre-requisites:
 
-      ```shell
-      export PYTHON_KEYRING_BACKEND=keyring.backends.null.Keyring
-      poetry install
-      ```
+         ```shell
+         sudo apt install -y libatlas-base-dev libhdf5-dev libopenblas-dev
+         ```
 
-      should work. See [GitHub issue](https://github.com/python-poetry/poetry/issues/1917) for further details.
+      1. Fix pyproject.toml manually:
+
+         Change the primary poetry packages source from `PyPI` to `piwheels`:
+
+         From:
+
+         ```toml
+         [[tool.poetry.source]]
+         name = "piwheels.org"
+         url = "https://www.piwheels.org/simple"
+         priority = "supplemental"
+
+         [[tool.poetry.source]]
+         name = "PyPI"
+         priority = "primary"
+         ```
+
+         To:
+
+         ```toml
+         [[tool.poetry.source]]
+         name = "piwheels.org"
+         url = "https://www.piwheels.org/simple"
+         priority = "primary"
+
+         [[tool.poetry.source]]
+         name = "PyPI"
+         priority = "supplemental"
+         ```
+
+         Delete the `poetry.lock` file
+
+         ```shell
+         rm poetry.lock
+         ```
+
+      1. Most likely you will run into `KeyRing` errors when installing over ssh on raspberry pi.
+
+         To get around it:
+
+         ```shell
+         export PYTHON_KEYRING_BACKEND=keyring.backends.null.Keyring
+         poetry install
+         ```
+
+         should work. See [GitHub issue](https://github.com/python-poetry/poetry/issues/1917) for further details.
+
+      1. Install the pre-requisites: `sudo apt install -y libatlas-base-dev libhdf5-dev libopenblas-dev`
+
+      1. Enable legacy camera support: Using `sudo raspi-config` enable `Legacy Camera Support`. This mode is going to be
+         deprecated. See [use legacy](https://github.com/opencv/opencv/issues/22820). This mode is used in the code as it offers
+         the most portability across operating systems.
+
+         **Note**: If you have Raspberry Pi Camera Module v3 or later this won't work. To avoid this, we have to use `picamera2`
+         which uses `libcamera`. See [picamera2 examples](https://github.com/raspberrypi/picamera2/blob/main/examples/opencv_face_detect_3.py).
+
+      1. VNC or Desktop Display mode:
+
+         To see the program working you need to login to the Raspberry PI Desktop. These are the steps that I had to take
+         to make it work.
+
+         1. Install `sudo apt install xrdp`
+         1. Add a new user, `sudo adduser pygpt` and RDP using as the new user. `RDP` session should not show a black screen now.
+            (I have seen this problem before where the files needed for X window session are not created by default. When you do add a new user
+            after installing `xrdp` then the files get created and everything works like magic. ).
+            See [OMG - it saved me so much time](https://www.reddit.com/r/raspberry_pi/comments/qw1cdw/raspberry_pi_4_xrdp_windows_10_remote_desktop/).
 
    1. Windows:
       Most likely you will run into `No backend available` errors.
@@ -92,7 +158,6 @@ To use `main.py`:
 
 This script will utilize the camera to detect and track faces, and control the T-Shirt launcher based on the tracked positions.
 
-
 ### Headless Mode Operation
 
 #### Overview