Add note to migration docs on silent batch mode
A previous change removed silent batch mode for the plugin
installer. This commit adds a note to the migration docs regarding this
change.
@@ -18,3 +18,14 @@ save disk space. As a consequence, database files had to be loaded in memory. No
that are stored uncompressed as `.mmdb` files which allows to memory-map them and save heap memory. Any
custom database files must also be stored uncompressed. Consequently, the `database_file` property in any
ingest pipelines that use the Geoip Processor must refer to the uncompressed database files as well.
+
+==== Using the plugin installer without a TTY
+
+The Elasticsearch plugin installer (`elasticsearch-plugin install`) would
+previously silently accept additional security permissions required by a plugin
+if standard input was closed or there was no TTY attached (e.g., `docker exec
+<container ID> elasticsearch-plugin install`). This silent accepting of
+additional security permissions has been removed. Now, a user must deliberately
+accept these permissions either by keeping standard input open and attaching a
+TTY (i.e., using interactive mode to accept the permissions), or by passing the
+`--batch` flag.
