Update docstring of image_encoder.py

minor docstring fix

Author: Xrenya

segment_anything/modeling/image_encoder.py

@@ -144,7 +144,7 @@ def __init__(
             rel_pos_zero_init (bool): If True, zero initialize relative positional parameters.
             window_size (int): Window size for window attention blocks. If it equals 0, then
                 use global attention.
-            input_size (int or None): Input resolution for calculating the relative positional
+            input_size (tuple(int, int) or None): Input resolution for calculating the relative positional
                 parameter size.
         """
         super().__init__()
@@ -201,7 +201,7 @@ def __init__(
             qkv_bias (bool:  If True, add a learnable bias to query, key, value.
             rel_pos (bool): If True, add relative positional embeddings to the attention map.
             rel_pos_zero_init (bool): If True, zero initialize relative positional parameters.
-            input_size (int or None): Input resolution for calculating the relative positional
+            input_size (tuple(int, int) or None): Input resolution for calculating the relative positional
                 parameter size.
         """
         super().__init__()