Fix a typo, consistently spell ASCII in all caps, and insert blank

lines between paragraphs in Mark Hammond's news item about the default
encoding in posixmodule.  Resist the temptation to reflow paragraphs.

Misc/NEWS

@@ -6,9 +6,10 @@ Core
 - Some operating systems now support the concept of a default Unicode
   encoding for file system operations.  Notably, Windows supports 'mbcs'
   as the default.  The Macintosh will also adopt this concept in the medium
-  term, altough the default encoding for that platform will be other than
+  term, although the default encoding for that platform will be other than
   'mbcs'.
-  On operating system that support non-ascii filenames, it is common for
+
+  On operating system that support non-ASCII filenames, it is common for
   functions that return filenames (such as os.listdir()) to return Python
   string objects pre-encoded using the default file system encoding for
   the platform.  As this encoding is likely to be different from Python's
@@ -16,6 +17,7 @@ Core
   it back to the Operating System would result in a Unicode error, as Python
   would attempt to use its default encoding (generally ASCII) rather than
   the default encoding for the file system.
+
   In general, this change simply removes surprises when working with
   Unicode and the file system, making these operations work as you expect,
   increasing the transparency of Unicode objects in this context.