Adding change log for excluded location feature (#40764)

* Adding change log for excluded location feature

* Update sdk/cosmos/azure-cosmos/CHANGELOG.md

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Co-authored-by: Kushagra Thapar <[email protected]>

Author: allenkim0129

sdk/cosmos/azure-cosmos/CHANGELOG.md

@@ -5,6 +5,7 @@
 #### Features Added
 * Added ability to set `throughput_bucket` header at the client level and for all requests. See [PR 40340](https://github.com/Azure/azure-sdk-for-python/pull/40340).
 * Added ability to use Filters from Logging module on Diagnostics Logging based on Http request/response related attributes. See [PR 39897](https://github.com/Azure/azure-sdk-for-python/pull/39897).
+* Added ability to use `excluded_locations` on client level and document API request level. See [PR 40298](https://github.com/Azure/azure-sdk-for-python/pull/40298) 
 
 #### Breaking Changes