Add descriptions for all the faps (#13)

Author: Astra

.catalog/README.md

@@ -1,7 +1,7 @@
-Just run the app and hold your Flipper Zero near the reader. The following icons may appear on the screen:
+# NFC&LFRFID Field Detector
 
-- NFC icon - the reader uses the NFC technology, operating at 13.56 MHz.
-- RFID icon - the reader uses the RFID technology, operating at 125 kHz. For RFID readers, the app displays the estimated frequency the reader operates at.
-- Both NFC and RFID icons - the reader uses both technologies.
+This application allows you to detect the presence of NFC and LF RFID fields. It can be used to check what technology is used in a reader that you don't have documentation for, or to check whether a reader is working properly.
 
+## Usage
 
+Open the app and bring your Flipper Zero up to the reader. The app will display the detected field type (NFC or LF RFID). For LF RFID, the app will also display the exact frequency of the field. If the reader is using both NFC and LF RFID, the app will display both.