fix ssdlite model class link in doc (#8318)

Co-authored-by: Nicolas Hug <[email protected]>

Author: nihui

docs/source/models/ssdlite.rst

@@ -17,7 +17,7 @@ The following model builders can be used to instantiate a SSD Lite model, with o
 without pre-trained weights. All the model builders internally rely on the
 ``torchvision.models.detection.ssd.SSD`` base class. Please refer to the `source
 code
-<https://github.com/pytorch/vision/blob/main/torchvision/models/detection/ssd.py>`_ for
+<https://github.com/pytorch/vision/blob/main/torchvision/models/detection/ssdlite.py>`_ for
 more details about this class.
 
 .. autosummary::