v1.5.1 to add example and fix compile error

#### Releases v1.5.1

1. Add example [MQTT_And_OTA_Ethernet](https://github.com/khoih-prog/WebServer_WT32_ETH01/tree/main/examples/MQTT_And_OTA_Ethernet) to demo how to use OTA. Check [Added MQTT and OTA over Ethernet example to examples folder #9](#9)
2. Fix compile error for examples [serveStatic](https://github.com/khoih-prog/WebServer_WT32_ETH01/tree/main/examples/serveStatic) and [serveStaticLoadFile](https://github.com/khoih-prog/WebServer_WT32_ETH01/tree/main/examples/serveStaticLoadFile) to use built-in LittleFS library for new ESP32 cores
3. Fix compile error for examples [ESP32_FS_EthernetWebServer](https://github.com/khoih-prog/WebServer_WT32_ETH01/tree/main/examples/ESP32_FS_EthernetWebServer) if WT32_ETH01 is selected as A0 (and many pins) not defined in new ESP32 cores

Author: khoih-prog

README.md

@@ -188,7 +188,7 @@ You can also use this link [![arduino-library-badge](https://www.ardu-badge.com/
 
 1. Install [VS Code](https://code.visualstudio.com/)
 2. Install [PlatformIO](https://platformio.org/platformio-ide)
-3. Install [**WebServer_WT32_ETH01** library]((https://registry.platformio.org/libraries/khoih-prog/WebServer_WT32_ETH01) by using [Library Manager]((https://registry.platformio.org/libraries/khoih-prog/WebServer_WT32_ETH01/installation). Search for WebServer_WT32_ETH01 in [Platform.io Author's Libraries](https://platformio.org/lib/search?query=author:%22Khoi%20Hoang%22)
+3. Install [**WebServer_WT32_ETH01** library](https://registry.platformio.org/libraries/khoih-prog/WebServer_WT32_ETH01) by using [Library Manager](https://registry.platformio.org/libraries/khoih-prog/WebServer_WT32_ETH01/installation). Search for WebServer_WT32_ETH01 in [Platform.io Author's Libraries](https://platformio.org/lib/search?query=author:%22Khoi%20Hoang%22)
 4. Use included [platformio.ini](platformio/platformio.ini) file from examples to ensure that all dependent libraries will installed automatically. Please visit documentation for the other options and examples at [Project Configuration File](https://docs.platformio.org/page/projectconf.html)
 
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