Use three-space indent for arrayFilters option description

Author: jmikola

docs/includes/apiargs-MongoDBCollection-common-option.yaml

@@ -2,8 +2,8 @@ arg_name: option
 name: arrayFilters
 type: array
 description: |
-  An array of filter documents that determines which array elements to modify
-  for an update operation on an array field.
+   An array of filter documents that determines which array elements to modify
+   for an update operation on an array field.
 interface: phpmethod
 operation: ~
 optional: true