[MTD] [NAND] nand_base.c fix broken link

replace with working link from nand Kconfig help text
fixes bugzilla 7815
Signed-off-by: Nmaximilian attems <max@stro.at>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

drivers/mtd/nand/nand_base.c

@@ -7,7 +7,7 @@
  *   Basic support for AG-AND chips is provided.
  *
  *	Additional technical information is available on
- *	http://www.linux-mtd.infradead.org/tech/nand.html
+ *	http://www.linux-mtd.infradead.org/doc/nand.html
  *
  *  Copyright (C) 2000 Steven J. Hill (sjhill@realitydiluted.com)
  *		  2002-2006 Thomas Gleixner (tglx@linutronix.de)