[fbsync] Add FasterRCNN improved weights (#5763)

Summary:
* Add FasterRCNN improved weights

* Add recipe URL

* Update publication_year field

(Note: this ignores all push blocking failures!)

Reviewed By: jdsgomes, NicolasHug

Differential Revision: D36095675

fbshipit-source-id: e8513c22da8e14419de0749b8085ee587ff11d84

Author: YosuaMichael

torchvision/models/detection/faster_rcnn.py

@@ -393,7 +393,18 @@ class FasterRCNN_ResNet50_FPN_Weights(WeightsEnum):
 
 
 class FasterRCNN_ResNet50_FPN_V2_Weights(WeightsEnum):
-    pass
+    COCO_V1 = Weights(
+        url="https://download.pytorch.org/models/fasterrcnn_resnet50_fpn_v2_coco-dd69338a.pth",
+        transforms=ObjectDetection,
+        meta={
+            **_COMMON_META,
+            "publication_year": 2021,
+            "num_params": 43712278,
+            "recipe": "https://github.com/pytorch/vision/pull/5763",
+            "map": 46.7,
+        },
+    )
+    DEFAULT = COCO_V1
 
 
 class FasterRCNN_MobileNet_V3_Large_FPN_Weights(WeightsEnum):