Added missing API references (#7553)

API docs changes according to the PR review
Contribution message updated

.gitignore

@@ -32,6 +32,8 @@ boards.sloeber.txt
 # Ignore docs build (Sphinx)
 docs/build
 docs/source/_build
+__pycache__/
+_build/
 
 # Test log files
 *.log

docs/source/api/ble.rst

+###
+BLE
+###
+
+About
+-----
+
+.. note:: This is a work in progress project and this section is still missing. If you want to contribute, please see the `Contributions Guide <../contributing.html>`_.
+
+Examples
+--------
+
+To get started with BLE, you can try: 
+
+BLE Scan
+********
+
+.. literalinclude:: ../../../libraries/BLE/examples/BLE_scan/BLE_scan.ino
+    :language: arduino
+
+BLE UART
+********
+
+.. literalinclude:: ../../../libraries/BLE/examples/BLE_uart/BLE_uart.ino
+    :language: arduino
+
+Complete list of `BLE examples <https://github.com/espressif/arduino-esp32/tree/master/libraries/BLE/examples>`_. 

docs/source/api/bluetooth.rst

-#############
-Bluetooth API
-#############
+#########
+Bluetooth
+#########
+
+About
+-----
+
+.. note:: This is a work in progress project and this section is still missing. If you want to contribute, please see the `Contributions Guide <../contributing.html>`_.
+
+Examples
+--------
+
+To get started with Bluetooth, you can try: 
+
+Serial To Serial BT
+*******************
+
+.. literalinclude:: ../../../libraries/BluetoothSerial/examples/SerialToSerialBT/SerialToSerialBT.ino
+    :language: arduino
+
+BT Classic Device Discovery
+***************************
+
+.. literalinclude:: ../../../libraries/BluetoothSerial/examples/bt_classic_device_discovery/bt_classic_device_discovery.ino
+    :language: arduino
+
+Complete list of `Bluetooth examples <https://github.com/espressif/arduino-esp32/tree/master/libraries/BluetoothSerial/examples>`_. 

docs/source/api/deepsleep.rst

 ##########
 Deep Sleep
 ##########
+
+About
+-----
+
+.. note:: This is a work in progress project and this section is still missing. If you want to contribute, please see the `Contributions Guide <../contributing.html>`_.
+
+Examples
+--------
+
+To get started with Hall sensor, you can try:
+
+ExternalWakeUp
+**************
+
+.. literalinclude:: ../../../libraries/ESP32/examples/DeepSleep/ExternalWakeUp/ExternalWakeUp.ino
+    :language: arduino
+
+Timer Wake Up
+*************
+
+.. literalinclude:: ../../../libraries/ESP32/examples/DeepSleep/TimerWakeUp/TimerWakeUp.ino
+    :language: arduino

docs/source/api/espnow.rst

@@ -5,8 +5,22 @@ ESP-NOW
 ESP-NOW is a fast, connectionless communication technology featuring a short packet transmission.
 ESP-NOW is ideal for smart lights, remote control devices, sensors and other applications. 
 
-Example
--------
+.. note:: This is a work in progress project and this section is still missing. If you want to contribute, please see the `Contributions Guide <../contributing.html>`_.
+
+Examples
+--------
+
+ESP-NOW Master
+**************
+
+.. literalinclude:: ../../../libraries/ESP32/examples/ESPNow/Basic/Master/Master.ino
+    :language: arduino
+
+ESP-NOW Slave
+*************
+
+.. literalinclude:: ../../../libraries/ESP32/examples/ESPNow/Basic/Slave/Slave.ino
+    :language: arduino
 
 Resources
 ---------

docs/source/api/ethernet.rst

+########
+Ethernet
+########
+
+About
+-----
+
+.. note:: This is a work in progress project and this section is still missing. If you want to contribute, please see the `Contributions Guide <../contributing.html>`_.
+
+Examples
+--------
+
+To get started with Ethernet, you can try: 
+
+LAN8720
+*******
+
+.. literalinclude:: ../../../libraries/Ethernet/examples/ETH_LAN8720/ETH_LAN8720.ino
+    :language: arduino
+
+TLK110
+******
+
+.. literalinclude:: ../../../libraries/Ethernet/examples/ETH_TLK110/ETH_TLK110.ino
+    :language: arduino
+
+Complete list of `Ethernet examples <https://github.com/espressif/arduino-esp32/tree/master/libraries/Ethernet/examples>`_. 

docs/source/api/hall_sensor.rst

+###########
+Hall Sensor
+###########
+
+About
+-----
+
+.. note:: This is a work in progress project and this section is still missing. If you want to contribute, please see the `Contributions Guide <../contributing.html>`_.
+
+Example
+-------
+
+To get started with Hall sensor, you can try:
+
+Hall Sensor
+***********
+
+.. literalinclude:: ../../../libraries/ESP32/examples/HallSensor/HallSensor.ino
+    :language: arduino

docs/source/api/pulse_counter.rst

+#############
+Pulse Counter
+#############
+
+About
+-----
+
+.. note:: This peripheral is not supported yet by the Arduino API's.

docs/source/api/reset_reason.rst

 ############
 Reset Reason
 ############
+
+About
+-----
+
+.. note:: This is a work in progress project and this section is still missing. If you want to contribute, please see the `Contributions Guide <../contributing.html>`_.
+
+Example
+-------
+
+To get started with Reset Reason, you can try:
+
+Reset Reason
+************
+
+.. literalinclude:: ../../../libraries/ESP32/examples/ResetReason/ResetReason.ino
+    :language: arduino
\ No newline at end of file

docs/source/api/rmt.rst

+###
+RMT
+###
+
+About
+-----
+
+.. note:: This is a work in progress project and this section is still missing. If you want to contribute, please see the `Contributions Guide <../contributing.html>`_.
+
+Remote Control Transceiver (RMT) peripheral was designed to act as an infrared transceiver.
+
+Example
+-------
+
+To get started with RMT, you can try:
+
+RMT Write Neo Pixel
+*******************
+
+.. literalinclude:: ../../../libraries/ESP32/examples/RMT/RMTWriteNeoPixel/RMTWriteNeoPixel.ino
+    :language: arduino
+
+
+Complete list of `RMT examples <https://github.com/espressif/arduino-esp32/tree/master/libraries/ESP32/examples/RMT>`_. 

docs/source/api/sdio.rst

+####
+SDIO
+####
+
+About
+-----
+
+.. note:: This peripheral is not supported yet by the Arduino API's.

docs/source/api/sdmmc.rst

+######
+SD MMC
+######
+
+About
+-----
+
+.. note:: This is a work in progress project and this section is still missing. If you want to contribute, please see the `Contributions Guide <../contributing.html>`_.
+
+Example
+-------
+
+To get started with SD_MMC, you can try:
+
+SDMMC Test
+**********
+
+.. literalinclude:: ../../../libraries/SD_MMC/examples/SDMMC_Test/SDMMC_Test.ino
+    :language: arduino
+
+
+Complete list of `SD MMC examples <https://github.com/espressif/arduino-esp32/tree/master/libraries/SD_MMC/examples>`_. 

docs/source/api/spi.rst

+###
+SPI
+###
+
+About
+-----
+
+For some APIs, the reference to be used is the same as the Arduino Core.
+
+Arduino API Reference
+---------------------
+
+`SPI Reference <https://www.arduino.cc/reference/en/language/functions/communication/spi/>`_
+
+`SPI Description <https://docs.arduino.cc/learn/communication/spi>`_
+
+Example
+-------
+
+To get started with SPI, you can try:
+
+SPI Multiple Buses
+******************
+
+.. literalinclude:: ../../../libraries/SPI/examples/SPI_Multiple_Buses/SPI_Multiple_Buses.ino
+    :language: arduino