Update Doc/c-api/frame.rst

Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>

Author: ZeroIntensity

Doc/c-api/frame.rst

@@ -182,7 +182,9 @@ They exist solely for backwards compatibility.
    Prior to Python 3.13, this function would copy the :attr:`~frame.f_locals`
    attribute of *f* to the internal "fast" array of local variables, allowing
    changes in frame objects to be visible to the interpreter. If *clear* was
-   true, this function would clear exceptions.
+   changes in frame objects to be visible to the interpreter. If *clear* was
+   true, this function would process variables that were unset in the locals
+   dictionary.
 
    .. versionchanged:: 3.13
       This function now does nothing.