[doc, committed] small grammar error fix

[Sandra Loosemore]

This fix was suggested by David Wohlferd here:

https://gcc.gnu.org/ml/gcc-patches/2015-02/msg00377.html

I've checked it in as obvious.

-Sandra


2015-02-10  David Wohlferd  <d...@limegreensocks.com>
            Sandra Loosemore  <san...@codesourcery.com>

        gcc/
        * doc/extend.texi (Loop-Specific Pragmas): Fix grammar error.


2015-02-10  David Wohlferd  <d...@limegreensocks.com>
	    Sandra Loosemore  <san...@codesourcery.com>

	gcc/
	* doc/extend.texi (Loop-Specific Pragmas): Fix grammar error.