Updated link to DRF SearchFilter

Author: mtnntn

docs/usage.md

@@ -205,7 +205,7 @@ As this feature depends on `django-filter` you need to run
 #### SearchFilter
 
 To comply with JSON:API query parameter naming standards, DRF's
-[SearchFilter](https://django-rest-framework.readthedocs.io/en/latest/api-guide/filtering/#searchfilter) should
+[SearchFilter](https://www.django-rest-framework.org/api-guide/filtering/#searchfilter) should
 be configured to use a `filter[_something_]` query parameter. This can be done by default by adding the
 SearchFilter to `REST_FRAMEWORK['DEFAULT_FILTER_BACKENDS']` and setting `REST_FRAMEWORK['SEARCH_PARAM']` or
 adding the `.search_param` attribute to a custom class derived from `SearchFilter`.  If you do this and also