fixed broken link in README.rst #77

Job	Run time
build (all, ChangeUID)	1m 26s
build (all, DumpInfo)	1m 28s
build (all, firmware_check)	1m 25s
build (all, FixBrickedUID)	1m 28s
build (all, MifareClassicValueBlock)	1m 28s
build (all, MinimalInterrupt)	1m 34s
build (all, ReadUidMultiReader)	1m 26s
build (all, rfid_default_keys)	1m 30s
build (all, rfid_write_personal_data)	1m 25s
build (all, Ntag216_AUTH)	1m 25s
build (all, ReadNUID)	1m 26s
build (all, RFID-Cloner)	1m 38s
build (all, rfid_read_personal_data)	1m 30s
	19m 9s

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