Update the spec fo Dynamic Validators states

Author: Seulgi Kim

spec/Dynamic-Validator.md

@@ -222,11 +222,11 @@ candidates = [ [address, deposits, nominate_end_at]+ ], address asc
 pending_rewards = [ [withdraw_at, address, quantity]+ ], [withdraw_at, address] asc
 banned = [ address+ ], address asc
 jailed = [ [address, deposits, custody_until, kicked_at]+ ], address asc
-term_changed_block_number = block number
+term_id = [ block number, term id ]
 ```
 
 ### on TermEnd events
-1. Update `term_changed_block_number` to the current block number
+1. Update `term_id` to the current block number and the next term id
 3. Remove the expired candidates and give back the deposits
 3. Remove the jailed accounts if the current term is greater than `kicked_at` and give back the deposits
 4. Pay the pending rewards