add links to rfid

wiki/125khz-rfid.md

@@ -3,3 +3,10 @@
 Low-frequency proximity cards are widely used in access control systems around the world. It's pretty dumb, keeps only a short few-byte ID, and has no authentication mechanism, allowing it to be easily read, cloned, and emulated by anyone. A 125 kHz antenna is located on the bottom of Flipper's body — it can read the EM-4100 and HID Prox cards, save them to the memory and emulate any of the saved cards by choosing one from the menu. 
 
 You can also emulate the card by entering its ID manually, so you can easily send it to your friend in a text format. Thus, Flipper owners can exchange card dumps with each other remotely without ever touching a physical card.
+
+## Links
+
+* https://scanlime.org/2008/09/using-an-avr-as-an-rfid-tag/
+* [ESP8266 em4100 emulator](https://github.com/Crypter/ESP-RFID)
+* https://www.kickstarter.com/projects/1708444109/rfidler-a-software-defined-rfid-reader-writer-emul
+* https://github.com/AlexMalov/EasyKeyDublicatorRFID