[New Feature] Support SAM 2.1 (#59)

* support sam 2.1

* refine config path and ckpt path

* update README

sam2/utils/transforms.py

@@ -108,7 +108,7 @@ class SAM2Transforms(nn.Module):
                 f"{e}\n\nSkipping the post-processing step due to the error above. You can "
                 "still use SAM 2 and it's OK to ignore the error above, although some post-processing "
                 "functionality may be limited (which doesn't affect the results in most cases; see "
-                "https://github.com/facebookresearch/segment-anything-2/blob/main/INSTALL.md).",
+                "https://github.com/facebookresearch/sam2/blob/main/INSTALL.md).",
                 category=UserWarning,
                 stacklevel=2,
             )