v1.2.1 for ESP32_SC + LwIP W6100

#### Releases v1.2.1

1. Initial coding to support `ESP32_S2/S3/C3`-based boards using `LwIP W6100 Ethernet`. Sync with [WebServer_ESP32_SC_W5500 v1.2.1](https://github.com/khoih-prog/WebServer_ESP32_SC_W5500)
2. Use `allman astyle`

Author: khoih-prog

README.md

@@ -16,6 +16,7 @@
 
 * [Why do we need this WebServer_ESP32_SC_W6100 library](#why-do-we-need-this-WebServer_ESP32_SC_W6100-library)
   * [Features](#features)
+  * [Sibling libraries](#Sibling-libraries)
   * [Currently supported Boards](#currently-supported-boards)
 * [Changelog](changelog.md)
 * [Prerequisites](#prerequisites)