add 125k text from kickstarter

wiki/125khz-rfid.md

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+# 125 kHz RFID
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+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. 
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+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.