gh-91485: Avoid unnecessary use of non-Python syntax in io docs (GH-101177)

(cherry picked from commit 783d1bc)

Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>

Author: miss-islington

Doc/library/io.rst

@@ -1015,8 +1015,8 @@ Text I/O
 
       .. versionadded:: 3.7
 
-   .. method:: reconfigure(*[, encoding][, errors][, newline][, \
-                           line_buffering][, write_through])
+   .. method:: reconfigure(*, encoding=None, errors=None, newline=None, \
+                           line_buffering=None, write_through=None)
 
       Reconfigure this text stream using new settings for *encoding*,
       *errors*, *newline*, *line_buffering* and *write_through*.