tempfile: Fix docstring. Issue #21397, patch by R. David Murray.

Lib/tempfile.py

 """Temporary files.
 
 This module provides generic, low- and high-level interfaces for
-creating temporary files and directories.  The interfaces listed
-as "safe" just below can be used without fear of race conditions.
-Those listed as "unsafe" cannot, and are provided for backward
-compatibility only.
+creating temporary files and directories.  All of the interfaces
+provided by this module can be used without fear of race conditions
+except for 'mktemp'.  'mktemp' is subject to race conditions and
+should not be used; it is provided for backward compatibility only.
 
 This module also provides some data items to the user:
 
@@ -544,7 +544,7 @@ class SpooledTemporaryFile:
         else:
             # Setting newline="\n" avoids newline translation;
             # this is important because otherwise on Windows we'd
-            # hget double newline translation upon rollover().
+            # get double newline translation upon rollover().
             self._file = _io.StringIO(newline="\n")
         self._max_size = max_size
         self._rolled = False