DOC: mention that float_format can be a function, not just a string (#27156)

Author: toobaz

pandas/core/generic.py

@@ -2796,8 +2796,10 @@ def to_latex(self, buf=None, columns=None, col_space=None, header=True,
             Formatter functions to apply to columns' elements by position or
             name. The result of each function must be a unicode string.
             List must be of length equal to the number of columns.
-        float_format : str, optional
-            Format string for floating point numbers.
+        float_format : one-parameter function or str, optional, default None
+            Formatter for floating point numbers. For example
+            ``float_format="%%.2f"`` and ``float_format="{:0.2f}".format`` will
+            both result in 0.1234 being formatted as 0.12.
         sparsify : bool, optional
             Set to False for a DataFrame with a hierarchical index to print
             every multiindex key at each row. By default, the value will be