Update CHANGELOG.md

Author: jon-batscha

CHANGELOG.md

@@ -12,7 +12,7 @@ NOTE: For more granular API-specific changes, please see our [API Changelog](htt
 ### Changed
 
 - To override the client-level `api_key` for a specific request, you will now need to use the following new keyword arg: `_request_auth`
-  - previously, this keyword arg was called `api_client`
+  - previously, this keyword arg was called `api_key`
 
 ### Fixed
 
@@ -131,4 +131,4 @@ NOTE: For more granular API-specific changes, please see our [API Changelog](htt
   - client name: `Client` → `KlaviyoAPI`
   - Client variable name in readme examples: `client` → `klaviyo`
   - Some functions have changed name
-- New resources and endpoints: see [API Changelog](https://developers.klaviyo.com/en/docs/changelog_) for full details
+- New resources and endpoints: see [API Changelog](https://developers.klaviyo.com/en/docs/changelog_) for full details