Update changelog with rule changes since 2024-06-27

Generated using 'make changelog' which auto-detected the latest entry
(2024-06-27) and identified all rule changes since then.

Entries added:
- Separate compatibility rules for input/output schemas (<<108>>)
- Deprecate x-extensible-enum (<<112>>)
- Fix mixup of rules 250 and 251
- Upgrade to OpenAPI 3.1 (<<101>>)
- Clarify GET-with-body and pagination interaction (<<148>>, <<161>>)
- Allow proprietary headers for Transactions Checkout (<<183>>)
- Update RFC links in <<243>>
- Clarify status codes 502/504 documentation (<<243>>)
- Improve Deprecation header format (<<189>>)

Author: SmilyOrg

chapters/changelog.adoc

@@ -17,6 +17,15 @@ to see a list of all changes.
 [[rule-changes]]
 == Rule Changes
 
+* `2025-11-27`: clearly separate compatibility rules for input and output schemas in <<108>>. ^https://github.com/zalando/restful-api-guidelines/pull/851[#851]^
+* `2025-11-27`: deprecate {x-extensible-enum} in favor of extensible enums using `examples` in <<112>>. ^https://github.com/zalando/restful-api-guidelines/pull/837[#837]^
+* `2025-10-08`: fix mixup of rules 250 and 251 in compatibility guidance. ^https://github.com/zalando/restful-api-guidelines/pull/852[#852]^
+* `2025-10-01`: upgrade to OpenAPI 3.1 as recommended version in <<101>>. ^https://github.com/zalando/restful-api-guidelines/pull/850[#850]^
+* `2025-05-27`: clarify interaction between {GET-with-body} and pagination in <<148>> and <<161>>. ^https://github.com/zalando/restful-api-guidelines/pull/841[#841]^
+* `2025-05-27`: allow proprietary headers for Transactions Checkout Platform in <<183>>. ^https://github.com/zalando/restful-api-guidelines/pull/843[#843]^
+* `2025-04-15`: update RFC links in <<243>> to use RFC 9110. ^https://github.com/zalando/restful-api-guidelines/commit/acf0dc5bf5573ae7a5bad4895ffb809c8e6890e5[acf0dc5]^
+* `2025-01-21`: clarify that status codes 502 and 504 should not be documented in <<243>>. ^https://github.com/zalando/restful-api-guidelines/commit/e6a4af821cac34f7ed3a4a7d1e83519a01368263[e6a4af8]^
+* `2024-09-18`: improve <<189>> to use RFC 9754 timestamp format for Deprecation header. ^https://github.com/zalando/restful-api-guidelines/pull/848[#848]^
 * `2024-06-27`: Clarified usage of {x-extensible-enum} for events in <<112>>. ^https://github.com/zalando/restful-api-guidelines/pull/807[#807]^
 * `2024-06-25`: Relaxed naming convention for date/time properties in <<235>>. ^https://github.com/zalando/restful-api-guidelines/pull/811[#811]^
 * `2024-06-11`: Linked <<127>> (duration / period) from <<238>>. ^https://github.com/zalando/restful-api-guidelines/pull/810[#810]^