[Reference][Contraints] Fix internal "fields" link

bicpi · bicpi · commit 5638aef2c6e1 · 2013-11-05T08:06:54.000+01:00
diff --git a/reference/constraints/Collection.rst b/reference/constraints/Collection.rst
@@ -316,7 +316,7 @@ allowMissingFields
 
 If this option is set to ``false`` and one or more fields from the `fields`_
 option are not present in the underlying collection, a validation error will
-be returned. If set to ``true``, it's ok if some fields in the `fields_`
+be returned. If set to ``true``, it's ok if some fields in the `fields`_
 option are not present in the underlying collection.
 
 missingFieldsMessage
