v1.2.0 to add support to LAN8720

### Releases v1.2.0

1. Add support to **LAN8720** Ethernet for many **STM32F4** (F407xx, NUCLEO_F429ZI) and **STM32F7** (DISCO_F746NG, NUCLEO_F746ZG, NUCLEO_F756ZG) boards.
2. Add LAN8720 examples
3. Add Packages' Patches for STM32 to use LAN8720 with STM32Ethernet and LwIP libraries

Author: khoih-prog

README.md

@@ -43,6 +43,7 @@
   * [1. How to select which built-in Ethernet or shield to use](#1-how-to-select-which-built-in-ethernet-or-shield-to-use)
     * [Select **one and only one** Ethernet library to use as follows:](#select-one-and-only-one-ethernet-library-to-use-as-follows)
     * [To use built-in LAN8742A](#to-use-built-in-lan8742a)
+    * [To use LAN8720](#to-use-lan8720)
     * [To use W5x00 Ethernet, for example using EthernetLarge library](#to-use-w5x00-ethernet-for-example-using-ethernetlarge-library)
     * [To use ENC28J60 Ethernet, using EthernetENC library (**NEW and Better**)](#to-use-enc28j60-ethernet-using-ethernetenc-library-new-and-better)
     * [To use ENC28J60 Ethernet, using UIPEthernet library](#to-use-enc28j60-ethernet-using-uipethernet-library)