projects: demo_esp: Add README documentation

Add README documentation for the DEMO_ESP project, covering hardware specifications, build setup, and supported platforms.

Signed-off-by: Joyce Velasco <Joyce.Velasco@analog.com>

doc/sphinx/source/projects/eval/demo_esp.rst

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+.. include:: ../../../../../projects/demo_esp/README.rst

projects/demo_esp/README.rst

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+Demo_ESP no-OS Example Project
+==============================
+
+.. contents::
+    :depth: 3
+
+Overview
+--------
+
+The ``demo_esp`` project provides a bare-metal software example for
+Wi-Fi and MQTT communication on ADUCM3029 and Maxim hardware platforms.
+It demonstrates basic connectivity functions and serves as a guide for
+integrating Wi-Fi and MQTT functionalities in no-OS environments.
+
+No-OS Build Setup
+-----------------
+
+Please see: `https://wiki.analog.com/resources/no-os/build`
+
+No-OS Supported Examples
+------------------------
+
+The initialization data used in the examples is taken out from the
+:git-no-OS:`Project Common Data Path </projects/demo_esp/src/common>`.
+
+The macros used in Common Data are defined in platform specific files
+found in the 
+:git-no-OS:`Project Platform Configuration Path </projects/demo_esp/src/platform>`.
+
+Basic example
+~~~~~~~~~~~~~
+
+The basic example code in the no-OS demo project for ADUCM3029 and Maxim
+platforms serves as a demonstration of connecting to a Wi-Fi network and
+an MQTT broker using a microcontroller. The file includes functions to
+initialize and connect to a Wi-Fi network, establish a connection with
+an MQTT broker, and send messages to the broker. The main function,
+``basic_example_main``, orchestrates these operations by first connecting 
+to Wi-Fi, then to the MQTT broker, and continuously sending data 
+to the broker in a loop.
+
+Key components of the code include the ``init_and_connect_wifi``
+function, which handles the initialization and connection to a Wi-Fi
+network, and the ``init_and_connect_to_mqtt_broker`` function, 
+which sets up a TCP socket connection to an MQTT broker and
+subscribes to a topic. The ``mqtt_message_handler`` function 
+processes incoming MQTT messages, and the ``send``
+function publishes messages to the broker. The code uses several
+external libraries for handling operations such as GPIO, UART, and
+network communication, indicated by the inclusion of headers like
+``no_os_gpio.h``, ``mqtt_client.h``, and ``tcp_socket.h``. The file is
+designed to be executed as part of a larger application, as indicated by
+the presence of the ``basic_example_main`` function, which serves as 
+the entry point for the example execution.
+
+In order to build the basic example, make sure you have the following
+configuration in the :git-no-OS:`Makefile <projects/demo_esp/Makefile>`:
+
+.. code-block:: bash
+
+   BASIC_EXAMPLE = y
+
+No-OS Supported Platforms
+-------------------------
+
+ADuCM Platform
+~~~~~~~~~~~~~~
+
+Hardware Used
+^^^^^^^^^^^^^
+
+- ADuCM3029 platform (EVAL-ADICUP3029) with on-board ESP8266 Wi-Fi
+  Module
+
+Connection
+^^^^^^^^^^
+
+- Connect the board to your PC using a standard micro-USB cable plugged
+  into the USB connector labeled P10.
+
+- Set the UART switch (S2) fully to the left (“USB” position). This
+  routes the UART signals to the USB connector, enabling read/write data
+  between the board and PC.
+
+- The board can be powered directly via the USB connection. Alternative
+  power sources include the DC barrel jack (+7V to +12V) or batteries
+  attached to the BT1 connector.
+
+- Push buttons: 3029_RESET offers hardware reset, 3029_BOOT with RESET
+  enables UART download mode for firmware flashing.
+
+Build Command
+^^^^^^^^^^^^^
+
+.. code-block:: bash
+
+   cd no-OS/projects/demo_esp
+
+   export PLATFORM=aducm3029
+
+   # to delete current build
+   make reset
+   # to build the project
+   make
+   # to flash the code
+   make run
+
+
+Maxim Platform
+~~~~~~~~~~~~~~
+
+Hardware Used
+^^^^^^^^^^^^^
+
+- MAX32690-based platform (either MAX32690EVKIT or AD-APARD32690-SL)
+- ESP Wifi Module (such as ESP8266)
+
+Connection
+^^^^^^^^^^
+
+- Connect the MAX32690 UART TX/RX/GND pins to the corresponding ESP
+  Wi-Fi module pins.
+
+================ ====================
+MAX32690 Pin     ESP Wi-Fi Module Pin
+UART_TX          RX
+UART_RX          TX
+GND              GND
+3.3V (if needed) VCC
+================ ====================
+
+- Use the on-board 3.3V supply to power the ESP module if your system
+  supports the current requirement.
+
+- After wiring up, configure and initialize the UART peripheral in your
+  MAX32690 firmware, matching the ESP module’s default baud rate
+  (typically 115200) and UART settings.
+
+Build Command
+^^^^^^^^^^^^^
+
+.. code-block:: bash
+
+   cd no-OS/projects/demo_esp
+
+   # to delete current build
+   make reset
+   # to build the project
+   make PLATFORM TARGET=max32690
+   # to flash the code
+   make run