Prepare changelog for 9.0.0 feature freeze (#2444)

Prepare changelog for 9.0.0 feature freeze

Co-authored-by: Taylor Swanson <[email protected]>

Author: mjwolf

CHANGELOG.next.md

@@ -12,23 +12,12 @@ Thanks, you're awesome :-) -->
 
 #### Breaking changes
 
-* Remove deprecated fields from previous major release; `process.pgid`, `service.node.role`, and inherited users. #2410
-
 #### Bugfixes
 
-* Fix link rendering issues and usage of http in links. #2423
-
 #### Added
-* Add `origin_referrer_url` and `origin_url` fields, which indicate the origin information to the file, process and dll schemas #2441
 
 #### Improvements
 
-* Promote beta fields to GA. #2411
-* Define base encoding of `x509.serial_number`. #2383
-* Restrict the encoding of `x509.serial_number` to base 16. #2398
-* Set synthetic_source_keep = none on fields that represent sets. #2422
-* Increase ignore_above value for url.query. #2424
-
 #### Deprecated
 
 ### Tooling and Artifact Changes
@@ -43,6 +32,41 @@ Thanks, you're awesome :-) -->
 
 #### Deprecated
 
+
+## 9.0.0 (Feature Freeze)
+
+### Schema Changes
+
+#### Breaking changes
+
+* Remove deprecated fields from previous major release; `process.pgid`, `service.node.role`, and inherited users. #2410
+
+#### Bugfixes
+
+* Fix link rendering issues and usage of http in links. #2423
+
+#### Added
+
+* Add `origin_referrer_url` and `origin_url` fields, which indicate the origin information to the file, process and dll schemas. #2441
+
+#### Improvements
+
+* Increase ignore_above value for url.query. #2424
+* Set synthetic_source_keep = none on fields that represent sets. #2422
+* Promote beta fields to GA. #2411
+* Restrict the encoding of `x509.serial_number` to base 16. #2398
+* Define base encoding of `x509.serial_number`. #2383
+
+### Tooling and Artifact Changes
+
+#### Added
+
+* Add mapping between ECS and OpenTelemetry. #2415
+
+#### Improvements
+
+* Update data_stream.yml with top level type: group. #2414
+
 <!-- All empty sections:
 
 ## Unreleased