Issue #16714: use 'raise' exceptions, don't 'throw'.

Patch by Serhiy Storchaka.
diff --git a/Lib/xml/sax/xmlreader.py b/Lib/xml/sax/xmlreader.py
index 46ee02b..74aa39a 100644
--- a/Lib/xml/sax/xmlreader.py
+++ b/Lib/xml/sax/xmlreader.py
@@ -68,7 +68,7 @@
 
         SAX parsers are not required to provide localization for errors
         and warnings; if they cannot support the requested locale,
-        however, they must throw a SAX exception. Applications may
+        however, they must raise a SAX exception. Applications may
         request a locale change in the middle of a parse."""
         raise SAXNotSupportedException("Locale support not implemented")