DOC: Update versionadded for 2.0 instead of 1.6 (pandas-dev#51002)

Author: phofl

pandas/core/frame.py

@@ -1902,7 +1902,7 @@ def to_dict(
             is 'tight') in the returned dictionary. Can only be ``False``
             when `orient` is 'split' or 'tight'.
 
-            .. versionadded:: 1.6.0
+            .. versionadded:: 2.0.0
 
         Returns
         -------

pandas/core/methods/to_dict.py

@@ -60,7 +60,7 @@ def to_dict(
         is 'tight') in the returned dictionary. Can only be ``False``
         when `orient` is 'split' or 'tight'.
 
-        .. versionadded:: 1.6.0
+        .. versionadded:: 2.0.0
 
     Returns
     -------