Bumps docs version to 8.9.1 (#2729)

Author: chriscressman

shared/versions/stack/8.9.asciidoc

@@ -1,12 +1,12 @@
-:version:                8.9.0
+:version:                8.9.1
 ////
 bare_version never includes -alpha or -beta
 ////
-:bare_version:           8.9.0
-:logstash_version:       8.9.0
-:elasticsearch_version:  8.9.0
-:kibana_version:         8.9.0
-:apm_server_version:     8.9.0
+:bare_version:           8.9.1
+:logstash_version:       8.9.1
+:elasticsearch_version:  8.9.1
+:kibana_version:         8.9.1
+:apm_server_version:     8.9.1
 :branch:                 8.9
 :minor-version:          8.9
 :major-version:          8.x