[3.13] gh-110383: Improve 'old string formatting' text in tutorial (GH-120219) (#120229)

(cherry picked from commit 225aab7)

Co-authored-by: Erlend E. Aasland <erlend@python.org>

Author: miss-islington

Doc/tutorial/inputoutput.rst

@@ -279,9 +279,11 @@ left with zeros.  It understands about plus and minus signs::
 Old string formatting
 ---------------------
 
-The % operator (modulo) can also be used for string formatting. Given ``'string'
-% values``, instances of ``%`` in ``string`` are replaced with zero or more
-elements of ``values``. This operation is commonly known as string
+The % operator (modulo) can also be used for string formatting.
+Given ``format % values`` (where *format* is a string),
+``%`` conversion specifications in *format* are replaced with
+zero or more elements of *values*.
+This operation is commonly known as string
 interpolation. For example::
 
    >>> import math