Added the README template for examples and libraries (#5228)

Typos fixed and added more details and instructions
Added README file to WiFiScan example
Review on the README template
Added link to DevKits

docs/EXAMPLE_README_TEMPLATE.md

+# Arduino-ESP32 Example/Library Name ==(REQUIRED)==
+
+==*Add a brief description about this example/library here!*==
+
+This example/library demonstrates how to create a new example README file.
+
+# Supported Targets ==(REQUIRED)==
+
+==*Add the supported devices here!*==
+
+Currently, this example supports the following targets.
+
+| Supported Targets | ESP32 | ESP32-S2 | ESP32-C3 |
+| ----------------- | ----- | -------- | -------- |
+
+## How to Use Example/Library ==(OPTIONAL)==
+
+==*Add a brief description on how to use this example.*==
+
+* How to install the Arduino IDE: [Install Arduino IDE](https://github.com/espressif/arduino-esp32/tree/master/docs/arduino-ide).
+
+### Hardware Connection ==(OPTIONAL)==
+
+==*Add a brief description about wiring or any other hardware specific connection.*==
+
+To use this example, you need to connect the LED to the `GPIOx`.
+
+SDCard GPIO connection scheme:
+
+| SDCard Pin | Function | GPIO |
+| ----------- | -------- | ------ |
+| 1 | CS | GPIO5 |
+| 2 | DI/MOSI | GPIO23 |
+| 3 | VSS/GND | GND |
+| 4 | VDD/3V3 | 3V3 |
+| 5 | SCLK | GPIO18 |
+| 6 | VSS/GND | GND |
+| 7 | DO/MISO | GPIO19 |
+
+To add images, please create a folder `_asset` inside the example folder to add the relevant images.
+
+### Configure the Project ==(OPTIONAL)==
+
+==*Add a brief description about this example here!*==
+
+Set the LED GPIO by changing the `LED_BUILTIN` value in the function `pinMode(LED_BUILTIN, OUTPUT);`. By default, the GPIO is: `GPIOx`.
+
+#### Example for the GPIO4:
+
+==*Add some code explanation if relevant to the example.*==
+
+```cpp
+// the setup function runs once when you press reset or power the board
+void setup() {
+// initialize digital pin 4 as an output.
+pinMode(4, OUTPUT);
+}
+```
+
+#### Using Arduino IDE
+
+To get more information about the Espressif boards see [Espressif Development Kits](https://www.espressif.com/en/products/devkits).
+
+* Before Compile/Verify, select the correct board: `Tools -> Board`.
+* Select the COM port: `Tools -> Port: xxx` where the `xxx` is the detected COM port.
+
+#### Using Platform IO
+
+* Select the COM port: `Devices` or setting the `upload_port` option on the `platformio.ini` file.
+
+## Example/Log Output ==(OPTIONAL)==
+
+==*Add the log/serial output here!*==
+
+```
+ets Jul 29 2019 12:21:46
+
+rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
+configsip: 0, SPIWP:0xee
+clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
+mode:DIO, clock div:1
+load:0x3fff0030,len:1412
+load:0x40078000,len:13400
+load:0x40080400,len:3672
+entry 0x400805f8
+ESP32 Chip model = ESP32-D0WDQ5 Rev 3
+This chip has 2 cores
+Chip ID: 3957392
+```
+
+## Troubleshooting ==(REQUIRED)==
+
+==*Add specific issues you may find by using this example here!*==
+
+***Important: Make sure you are using a good quality USB cable and that you have a reliable power source***
+
+* **LED not blinking:** Check the wiring connection and the IO selection.
+* **Programming Fail:** If the programming/flash procedure fails, try reducing the serial connection speed.
+* **COM port not detected:** Check the USB cable and the USB to Serial driver installation.
+
+If the error persist, you can ask for help at the official [ESP32 forum](https://esp32.com) or see [Contribute](#contribute).
+
+## Contribute ==(REQUIRED)==
+
+==*Do not change! Keep as is.*==
+
+To know how to contribute to this project, see [How to contribute.](https://github.com/espressif/arduino-esp32/blob/master/CONTRIBUTING.rst)
+
+If you have any **feedback** or **issue** to report on this example/library, please open an issue or fix it by creating a new PR. Contributions are more than welcome!
+
+Before creating a new issue, be sure to try the Troubleshooting and to check if the same issue was already created by someone else.
+
+## Resources ==(REQUIRED)==
+
+==*Do not change here! Keep as is or add only relevant documents/info for this example. Do not add any purchase link/marketing stuff*==
+
+* Official ESP32 Forum: [Link](https://esp32.com)
+* Arduino-ESP32 Official Repository: [espressif/arduino-esp32](https://github.com/espressif/arduino-esp32)
+* ESP32 Datasheet: [Link to datasheet](https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf)
+* ESP32-S2 Datasheet: [Link to datasheet](https://www.espressif.com/sites/default/files/documentation/esp32-s2_datasheet_en.pdf)
+* ESP32-C3 Datasheet: [Link to datasheet](https://www.espressif.com/sites/default/files/documentation/esp32-c3_datasheet_en.pdf)
+* Official ESP-IDF documentation: [ESP-IDF](https://idf.espressif.com)

libraries/WiFi/examples/WiFiScan/README.md

+# WiFiScan Example
+
+This example demonstrates how to use the WiFi library to scan available WiFi networks and print the results.
+
+# Supported Targets
+
+Currently this example supports the following targets.
+
+| Supported Targets | ESP32 | ESP32-S2 | ESP32-C3 |
+| ----------------- | ----- | -------- | -------- |
+
+## How to Use Example
+
+* How to install the Arduino IDE: [Install Arduino IDE](https://github.com/espressif/arduino-esp32/tree/master/docs/arduino-ide).
+
+#### Using Arduino IDE
+
+* Before Compile/Verify, select the correct board: `Tools -> Board`.
+* Select the COM port: `Tools -> Port: xxx` where the `xxx` is the detected COM port.
+
+#### Using Platform IO
+
+* Select the COM port: `Devices` or setting the `upload_port` option on the `platformio.ini` file.
+
+## Example/Log Output
+
+```
+ets Jul 29 2019 12:21:46
+
+rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
+configsip: 0, SPIWP:0xee
+clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
+mode:DIO, clock div:1
+load:0x3fff0030,len:1412
+load:0x40078000,len:13400
+load:0x40080400,len:3672
+entry 0x400805f8
+Setup done
+scan start
+scan done
+17 networks found
+1: IoTNetwork (-62)*
+2: WiFiSSID (-62)*
+3: B3A7992 (-63)*
+4: WiFi (-63) 
+5: IoTNetwork2 (-64)*
+...
+```
+
+## Troubleshooting
+
+***Important: Be sure you're using a good quality USB cable and you have enought power source for your project.***
+
+* **Programming Fail:** If the programming/flash procedure fails, try to reduce the serial connection speed.
+* **COM port not detected:** Check the USB cable connection and the USB to Serial driver installation.
+
+If the error persist, you can ask help at the official [ESP32 forum](https://esp32.com) or see [Contribute](#contribute).
+
+## Contribute
+
+To know how to contribute to this project, see [How to contribute.](https://github.com/espressif/arduino-esp32/blob/master/CONTRIBUTING.rst)
+
+If you have any **feedback** or **issue** to report on this example/library, please open an issue or fix it by creating a new PR. Contributions are more than welcome!
+
+Before creating a new issue, be sure to try the Troubleshooting and to check if the same issue was already created by someone else.
+
+## Resources
+
+* Arduino-ESP32 Official Repository: [espressif/arduino-esp32](https://github.com/espressif/arduino-esp32)
+* ESP32 Datasheet: [Link to datasheet](https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf)
+* ESP32-S2 Datasheet: [Link to datasheet](https://www.espressif.com/sites/default/files/documentation/esp32-s2_datasheet_en.pdf)
+* ESP32-C3 Datasheet: [Link to datasheet](https://www.espressif.com/sites/default/files/documentation/esp32-c3_datasheet_en.pdf)
+* Official ESP-IDF documentation: [ESP-IDF](https://idf.espressif.com)