fix: gas from step 3 -> step 4

neps/nep-0539.md

@@ -223,7 +223,7 @@ The new chunk execution then follows this order.
       the local shard.
 5. Execute receipts in the order of `local`, `delayed`, `incoming`, `yield-resume time-out`.
     - Don't stop before all receipts are executed or more than 1000 Tgas have
-      been burnt. Burnt gas includes the burnt gas from step 3.
+      been burnt. Burnt gas includes the burnt gas from step 4.
     - Outgoing receipts up to what is left in
       `outgoing_gas_limit[receipt.receiver]` per shard (after step 3) go to the
       outgoing receipts list of the chunk.