Added documentation for meta usage and for renderer class

Author: jerel

docs/api.md

@@ -7,3 +7,34 @@
 Add this mixin to a view to override `get_queryset` to automatically filter
 records by `ids[]=1&ids[]=2` in URL query params.
 
+## rest_framework_json_api.renderers.JSONRenderer
+
+The `JSONRenderer` exposes a number of methods that you may override if you need
+highly custom rendering control.
+
+#### extract_attributes
+
+`extract_attributes(fields, resource)`
+
+Builds the `attributes` object of the JSON API resource object.
+
+#### extract_relationships(fields, resource, resource_instance)
+
+Builds the `relationships` top level object based on related serializers.
+
+#### extract_included(fields, resource, resource_instance, included_resources)
+
+Adds related data to the top level `included` key when the request includes `?include=example,example_field2`
+
+#### extract_meta(serializer, resource)
+
+Gathers the data from serializer fields specified in `meta_fields` and adds it to the `meta` object.
+
+#### extract_root_meta(serializer, resource, meta)
+
+Calls a `get_root_meta` function on a serializer, if it exists.
+
+#### build_json_resource_obj(fields, resource, resource_instance, resource_name)
+
+Builds the resource object (type, id, attributes) and extracts relationships.
+

docs/usage.md

@@ -229,10 +229,28 @@ When set to pluralize:
 Both `JSON_API_PLURALIZE_RELATION_TYPE` and `JSON_API_FORMAT_RELATION_KEYS` can be combined to 
 achieve different results.
 
+### Meta
+
+You may add metadata to the rendered json in two different ways: `meta_fields` and `get_root_meta`.
+
+On any `rest_framework_json_api.serializers.ModelSerializer` you may add a `meta_fields`
+property to the `Meta` class. This behaves in the same manner as the default
+`fields` property and will cause `SerializerMethodFields` or model values to be
+added to the `meta` object within the same `data` as the serializer.
+
+To add metadata to the top level `meta` object add:
+
+``` python
+def get_root_meta(self, obj):
+    return {
+        'size': len(obj)
+    }
+```
+to the serializer. It must return a dict and will be merged with the existing top level `meta`.
+
 <!-- 
 ### Relationships
 ### Links
 ### Included
 ### Errors
-### Meta
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