Documentation: fix admin-guide/README.rst minimum gcc version requirement

Fix minimum gcc version as specified in Documentation/process/changes.rst.

Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/admin-guide/README.rst

@@ -251,7 +251,7 @@ Configuring the kernel
 Compiling the kernel
 --------------------
 
- - Make sure you have at least gcc 3.2 available.
+ - Make sure you have at least gcc 4.6 available.
    For more information, refer to :ref:`Documentation/process/changes.rst <changes>`.
 
    Please note that you can still run a.out user programs with this kernel.