[DOCS] Add transform breaking changes (#79531)

docs/reference/migration/migrate_8_0.asciidoc

@@ -38,6 +38,7 @@ coming[8.0.0]
 * <<breaking_80_settings_changes>>
 * <<breaking_80_snapshots_changes>>
 * <<breaking_80_threadpool_changes>>
+* <<breaking_80_transform_changes>>
 * <<breaking_80_transport_changes>>
 * <<breaking_80_watcher_changes>>
 
@@ -141,6 +142,7 @@ include::migrate_8_0/security.asciidoc[]
 include::migrate_8_0/settings.asciidoc[]
 include::migrate_8_0/snapshots.asciidoc[]
 include::migrate_8_0/threadpool.asciidoc[]
+include::migrate_8_0/transform.asciidoc[]
 include::migrate_8_0/transport.asciidoc[]
 include::migrate_8_0/watcher.asciidoc[]
 include::migrate_8_0/migrate_to_java_time.asciidoc[]

docs/reference/migration/migrate_8_0/transform.asciidoc

@@ -0,0 +1,21 @@
+[discrete]
+[[breaking_80_transform_changes]]
+==== Transform changes
+
+//NOTE: The notable-breaking-changes tagged regions are re-used in the
+//Installation and Upgrade Guide
+
+//tag::notable-breaking-changes[]
+.{transforms-cap} created in 7.4 or earlier versions must be upgraded
+[%collapsible]
+====
+*Details* +
+Early beta versions of {transforms} had configuration information in a format
+that is no longer supported.
+
+
+*Impact* +
+Use the {ref}/upgrade-transforms.html[upgrade {transforms} API] to fix your
+{transforms}. This upgrade does not affect the source or destination indices.
+====
+// end::notable-breaking-changes[]

docs/reference/transform/apis/upgrade-transforms.asciidoc

@@ -32,7 +32,7 @@ major versions. However, over time, the format of {transform} configuration
 information may change. This API identifies {transforms} which have a legacy 
 configuration format and upgrades them to the latest version; including clean up 
 of the internal data structures that store {transform} state and checkpoints. 
-{transform-cap} upgrade does not effect the source and destination indices.
+{transform-cap} upgrade does not affect the source and destination indices.
 
 If a {transform} upgrade step fails, the upgrade stops, and an error is returned 
 about the underlying issue. Resolve the issue then re-run the process again. A