Update changelog for @metamask/gas-fee-controller@6 (#1405)

* Update changelog for `@metamask/gas-fee-controller@6`

The changelog has been updated to better describe the changes. A new
entry has been added for a newly discovered breaking change, and an
existing entry was updated to clarify when it applies.

* Fix typo

Co-authored-by: Elliot Winkler <elliot.winkler@gmail.com>

---------

Co-authored-by: Elliot Winkler <elliot.winkler@gmail.com>

packages/gas-fee-controller/CHANGELOG.md

@@ -12,6 +12,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **BREAKING:** The `getChainId` constructor parameter now expects a `Hex` return type rather than a decimal string ([#1367](https://github.com/MetaMask/core/pull/1367))
 - Add `@metamask/utils` dependency
 - **BREAKING:** The gas fee controller messenger now requires the `NetworkController:stateChange` event instead of the `NetworkController:providerConfigChange` event ([#1329](https://github.com/MetaMask/core/pull/1329))
+  - This does not apply if `onNetworkStateChange` and `getChainId` are provided to the constructor
+- **BREAKING:** The constructor parameter `onNetworkStateChange` now expects event handlers to be passed the full network state ([#1329](https://github.com/MetaMask/core/pull/1329))
+  - The type of the `onNetworkStateChange` parameter already expected the state to be provided, but it wasn't used before now
 - **BREAKING:** Update `@metamask/network-controller` dependency and peer dependency
 
 ## [5.0.0]