added changelog entry and comment

.changelog/unreleased/features/1587-enable-opt-in-chains-through-gov-proposals.md

@@ -0,0 +1,2 @@
+.changelog/unreleased/features/1587-enable-opt-in-chains-throughgov-proposals.md- Enable Opt In and Top N chains through gov proposals.
+  ([\#1587](https://github.com/cosmos/interchain-security/pull/1587))

x/ccv/provider/keeper/proposal.go

@@ -367,7 +367,11 @@ func (k Keeper) BeginBlockInit(ctx sdk.Context) {
 			ctx.Logger().Info("consumer client could not be created: %w", err)
 			continue
 		}
+
+		// Only set Top N at the moment a chain starts. If we were to do this earlier (e.g., during the proposal),
+		// then someone could create a bogus ConsumerAdditionProposal to override the Top N for a specific chain.
 		k.SetTopN(ctx, prop.ChainId, prop.Top_N)
+
 		// The cached context is created with a new EventManager so we merge the event
 		// into the original context
 		ctx.EventManager().EmitEvents(cachedCtx.EventManager().Events())