Fix documentation nits for decimal context managers.

Doc/lib/libdecimal.tex

@@ -448,27 +448,23 @@ active context.
 
 \begin{funcdesc}{localcontext}{\optional{c}}
   Return a context manager that will set the current context for
-  the active thread to a copy of \var{c} on entry to the with statement
-  and restore the previous context when exiting the with statement. If
+  the active thread to a copy of \var{c} on entry to the with-statement
+  and restore the previous context when exiting the with-statement. If
   no context is specified, a copy of the current context is used.
+  \versionadded{2.5}
 
-  For example the following code increases the current decimal precision
+  For example, the following code increases the current decimal precision
   by 42 places, performs a calculation, and then automatically restores
   the previous context:
 \begin{verbatim}
     from __future__ import with_statement
     import decimal
 
-    with decimal.localcontext() as ctx:
+    with localcontext() as ctx:
         ctx.prec = 42   # Perform a high precision calculation
         s = calculate_something()
     s = +s  # Round the final result back to the default precision
 \end{verbatim}
-
-  The context that is held by the context manager and made active in the
-  body of the \keyword{with} statement is a \emph{copy} of the context
-  you provide to this function, so modifying its attributes doesn't
-  affect anything except that temporary copy.
 \end{funcdesc}
 
 New contexts can also be created using the \class{Context} constructor

Doc/whatsnew/whatsnew25.tex

@@ -685,20 +685,19 @@ the block is complete.
 
 The \module{decimal} module's contexts, which encapsulate the desired
 precision and rounding characteristics for computations, provide a 
-\method{context_manager()} method for getting a context manager:
+\function{localcontext()} function for getting a context manager:
 
 \begin{verbatim}
-import decimal
+from decimal import Decimal, Context, localcontext
 
 # Displays with default precision of 28 digits
-v1 = decimal.Decimal('578')
-print v1.sqrt()
+v = Decimal('578')
+print v.sqrt()
 
-ctx = decimal.Context(prec=16) 
-with ctx.context_manager():
+with localcontext(Context(prec=16)):
     # All code in this block uses a precision of 16 digits.
     # The original context is restored on exiting the block.
-    print v1.sqrt()
+    print v.sqrt()
 \end{verbatim}
 
 \subsection{Writing Context Managers\label{context-managers}}