chore: import upstream snapshot with attribution

testing/generation/command_docs/synopses/alter_index.txt

@@ -0,0 +1,17 @@
+ALTER INDEX [ IF EXISTS ] $name$ RENAME TO $new_name$
+
+ALTER INDEX [ IF EXISTS ] $name$ SET TABLESPACE $tablespace_name$
+
+ALTER INDEX $name$ ATTACH PARTITION $index_name$
+
+ALTER INDEX $name$ [ NO ] DEPENDS ON EXTENSION $extension_name$
+
+ALTER INDEX [ IF EXISTS ] $name$ SET ( { $storage_parameter$ [ = $value$ ] } [ , ... ] )
+
+ALTER INDEX [ IF EXISTS ] $name$ RESET ( $storage_parameter$ [ , ... ] )
+
+ALTER INDEX [ IF EXISTS ] $name$ ALTER [ COLUMN ] $column_number$
+    SET STATISTICS $integer$
+
+ALTER INDEX ALL IN TABLESPACE $name$ [ OWNED BY $role_name$ [ , ... ] ]
+    SET TABLESPACE $new_tablespace$ [ NOWAIT ]