Unify blob store compress setting

Added breaking changes documentation on the removed
'repositories.fs.compress' setting.

This is a follow up on elastic#39073

docs/reference/migration/migrate_8_0.asciidoc

@@ -12,6 +12,7 @@ See also <<release-highlights>> and <<es-release-notes>>.
 coming[8.0.0]
 
 * <<breaking_80_mappings_changes>>
+* <<breaking_80_snapshots_changes>>
 
 [float]
 === Indices created before 7.0
@@ -29,4 +30,5 @@ Elasticsearch 7.x in order to be readable by Elasticsearch 8.x.
 
 =========================================
 
-include::migrate_8_0/mappings.asciidoc[]
+include::migrate_8_0/mappings.asciidoc[]
+include::migrate_8_0/snapshots.asciidoc[]

docs/reference/migration/migrate_8_0/snapshots.asciidoc

@@ -0,0 +1,13 @@
+[float]
+[[breaking_80_snapshots_changes]]
+=== Snapshot and Restore changes
+
+[float]
+==== Deprecated node level compress setting removed
+
+For shared file system repositories (`"type": "fs"`), the node level setting `repositories.fs.compress` could
+previously be used to enable compression for all shared file system repositories where `compress` was not specified.
+The `repositories.fs.compress` setting has been removed.
+
+Instead use the repository specific `compress` setting to enable compression. See <<modules-snapshots>> for information
+on the `compress` setting.