docs: Update changelogs for 8.12 release

CHANGELOG.asciidoc

@@ -1,4 +1,5 @@
 include::./changelogs/head.asciidoc[]
+include::./changelogs/8.12.asciidoc[]
 include::./changelogs/8.11.asciidoc[]
 include::./changelogs/8.10.asciidoc[]
 include::./changelogs/8.9.asciidoc[]

changelogs/8.12.asciidoc

@@ -0,0 +1,27 @@
+[[release-notes-head]]
+== APM version HEAD
+
+https://github.com/elastic/apm-server/compare/8.11\...main[View commits]
+
+[float]
+==== Breaking Changes
+- The unsupported apm_data_stream_migration ingest pipeline has been removed {pull}12102[12102].
+- "publish_ready" is always false in the "GET /" response until events are received by apm-server {pull}12150[12150]
+
+[float]
+==== Bug fixes
+- Switch built-in ILM rollover policies from max_size to max_primary_shard_size {pull}11729[11729].
+
+[float]
+==== Deprecations
+
+[float]
+==== Intake API Changes
+
+[float]
+==== Added
+- Update container base image to Ubuntu 22.04 {pull}11778[11778]
+- Add support for returning partial success response in OTLP input {pull}11883[11883]
+- Setting event timestamp from OTel observed timestamp when needed {pull}11935[11935]
+- Field mappings have been added for various formerly unindexed fields {pull}12102[12102]
+- We now assert that index templates are installed by attempting to create data streams {pull}12150[12150]

changelogs/head.asciidoc

@@ -1,16 +1,10 @@
 [[release-notes-head]]
 == APM version HEAD
 
-https://github.com/elastic/apm-server/compare/8.11\...main[View commits]
+https://github.com/elastic/apm-server/compare/8.12\...main[View commits]
 
 [float]
 ==== Breaking Changes
-- The unsupported apm_data_stream_migration ingest pipeline has been removed {pull}12102[12102].
-- "publish_ready" is always false in the "GET /" response until events are received by apm-server {pull}12150[12150]
-
-[float]
-==== Bug fixes
-- Switch built-in ILM rollover policies from max_size to max_primary_shard_size {pull}11729[11729].
 
 [float]
 ==== Deprecations
@@ -20,8 +14,3 @@ https://github.com/elastic/apm-server/compare/8.11\...main[View commits]
 
 [float]
 ==== Added
-- Update container base image to Ubuntu 22.04 {pull}11778[11778]
-- Add support for returning partial success response in OTLP input {pull}11883[11883]
-- Setting event timestamp from OTel observed timestamp when needed {pull}11935[11935]
-- Field mappings have been added for various formerly unindexed fields {pull}12102[12102]
-- We now assert that index templates are installed by attempting to create data streams {pull}12150[12150]

docs/release-notes.asciidoc

@@ -9,6 +9,7 @@ This section summarizes the changes in each release.
 
 **APM integration and APM Server**
 
+* <<release-notes-8.12>>
 * <<release-notes-8.11>>
 * <<release-notes-8.10>>
 * <<release-notes-8.9>>