DOCS: fix underline length

Author: githubalexliu

pandas/core/arrays/arrow/accessors.py

@@ -245,7 +245,7 @@ def dtypes(self) -> Series:
             The data type of each child field.
 
         See Also
-        -------
+        --------
         Series.dtype: Return the dtype object of the underlying data.
 
         Examples

pandas/core/series.py

@@ -1618,7 +1618,7 @@ def to_markdown(
             {klass} in Markdown-friendly format.
 
         See Also
-        -------
+        --------
         Series.to_frame : Rrite a text representation of object to the system clipboard.
         Series.to_latex : Render Series to LaTeX-formatted table.