fix: typo

polkadot-protocol/basics/randomness.md

@@ -27,7 +27,7 @@ Slots on Polkadot are discrete units of time, each lasting six seconds, and can
 
 In each slot, validators execute a "die roll" using a VRF. The VRF uses three inputs:
 
-1. A "secret key", unique to each validator, is used for the die roll
+1. A "secret key," unique to each validator, is used for the die roll
 2. An epoch randomness value, derived from the hash of VRF outputs from blocks two epochs ago (N-2), so past randomness influences the current epoch (N)
 3. The current slot number