bpo-13790: Change 'string' to 'specification' in format doc (GH-18690)

Author: terryjreedy

Doc/library/string.rst

@@ -302,9 +302,9 @@ specification is to be interpreted.
 Most built-in types implement the following options for format specifications,
 although some of the formatting options are only supported by the numeric types.
 
-A general convention is that an empty format string (``""``) produces
+A general convention is that an empty format specification produces
 the same result as if you had called :func:`str` on the value. A
-non-empty format string typically modifies the result.
+non-empty format specification typically modifies the result.
 
 The general form of a *standard format specifier* is:
 

Misc/NEWS.d/next/Documentation/2020-02-28-14-39-25.bpo-13790.hvLaRI.rst

@@ -0,0 +1 @@
+Change 'string' to 'specification' in format doc.