Add example to poll encoder and display value on I2C display (#963)

Co-authored-by: Milton Eduardo Sosa <milton@Miltons-MacBook-Pro.local>

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+# STM32F411CEU6 encoder polling and LCD display 
+
+This example uses an STM32F411CEU6 microcontroller on the Blackpill board to interface with an I2C LCD display and a rotary encoder.
+
+
+## Features
+
+- **Rotary Encoder Integration**: Reads input from a rotary encoder to adjust a value.
+- **I2C LCD Display**: Displays the current encoder value on an I2C-connected HD44780 LCD.
+
+
+## Working principle
+The hardware task `tim2_timeout_interrupt_handler` polls the encoder state on each interrupt generated by TIM2, and updates the displayed value accordingly.
+
+
+## Code Overview
+
+### Key Components
+
+- **Knob Struct**: Placeholder for the rotary encoder and its current value.
+- **LCD I2C Communication**: Uses I2C protocol to communicate with the HD44780 LCD.
+- **Timers**: Utilizes TIM1 for delays and TIM2 for polling the rotary encoder.
+
+### Important Constants
+
+- `LCD_I2C_ADDRESS`: The I2C address of the LCD display.
+
+### Initialization
+
+- **System Clock**: Configured to use an external 25 MHz clock.
+- **GPIO Setup**: Configures GPIO pins for the LED, rotary encoder, and I2C communication.
+- **I2C Initialization**: Sets up the I2C bus for LCD communication.
+- **LCD Initialization**: Initializes the LCD and displays initial messages.
+- **Timer Setup**: Configures TIM2 at 2 kHz and generate interrupts.
+
+### Tasks and Handlers
+
+- **idle**: Background task that runs when no other tasks are active.
+- **tim2_timeout_interrupt_handler**: Handles interrupts generated by TIM2, updates the rotary encoder value, and displays the value on the LCD.
+
+### Utility Functions
+
+- `u8_to_str(n: u8) -> [u8; 3]`: Converts an 8-bit integer to a 3-character string representation.
+
+
+## Dependencies
+
+- **hd44780-driver**: Driver for HD44780 LCD over I2C.
+- **rotary_encoder_embedded**: Library for handling rotary encoders.
+- **defmt**: Logging framework for embedded systems.
+
+
+## How-to
+
+### Build
+Run `cargo build --release` to compile the code. If you run it for the first time, it will take some time to download and compile dependencies.
+
+### Run
+Install `probe-rs` and configure it using the [debugging extension for VScode](https://probe.rs/docs/tools/debugger/).  
+The output should look like this:
+
+[![IMAGE ALT TEXT HERE](https://img.youtube.com/vi/nn75gWDhHn0/0.jpg)](https://www.youtube.com/watch?v=nn75gWDhHn0)
+
+