Add ESP8266_Ethernet_Manager library (#2223)

#### Releases v1.0.0

1. Initial coding to port `synchronous` [ESP_WiFiManager](https://github.com/khoih-prog/ESP_WiFiManager) to ESP8266 boards using `LwIP W5500 / W5100(S) / ENC28J60 Ethernet`.
2. Use `allman astyle`

Author: khoih-prog

repositories.txt

@@ -5418,3 +5418,4 @@ https://github.com/shyd/Arduino-SerialCommand
 https://github.com/dlyckelid/IOExpander-TLA2518
 https://github.com/khoih-prog/ESP32_Ethernet_Manager
 https://github.com/khoih-prog/AsyncESP8266_Ethernet_Manager
+https://github.com/khoih-prog/ESP8266_Ethernet_Manager