docs: update changelog on halo2 verifier contract (#2001)

Author: jonathanpwang

CHANGELOG.md

@@ -13,6 +13,8 @@ and this project follows a versioning principles documented in [VERSIONING.md](.
 
 ### Changed
 - (Verifier) The `MultiStarkVerifyingKey`s for all existing App and Agg configs remain unchanged. However the serialized binary for the `AppVerifyingKey` has changed due to the removal of `as_offset` from `MemoryDimensions` (see below).
+- (Verifier) A fix was made to apply a missing permutation to the trace height constraints in the root verifier circuit's vkey. This changes the pre-vkey hash of the root verifier vkey for initializing Fiat-Shamir. This fix does not impact the security of existing root verifier vkeys generated through the SDK because root verifier proofs have fixed trace heights and these trace heights have been checked to satisfy all trace height constraints statically.
+- (Verifier/CLI) The `Halo2ProvingKey` and `Halo2Verifier.sol` verifier contract generated by the CLI now use `verifier_k = 23` instead of `24` (previous) for a smaller circuit.
 - (Toolchain) Removed `step` from `Program` struct because `DEFAULT_PC_STEP = 4` is always used.
 - (Config) The `SystemConfig` default now has `continuation_enabled: true` instead of the previous default of `false`. This is a **breaking change**.
 - (Config) The `clk_max_bits` field in `MemoryConfig` has been renamed to `timestamp_max_bits`.