DOC: Fix typo in to_html and to_string docs (#61555)

Author: datapythonista

pandas/io/formats/format.py

@@ -114,7 +114,7 @@
         columns : array-like, optional, default None
             The subset of columns to write. Writes all columns by default.
         col_space : %(col_space_type)s, optional
-            %(col_space)s.
+            %(col_space)s
         header : %(header_type)s, optional
             %(header)s.
         index : bool, optional, default True