docs: ramdisk/initrd/initramfs corrections

initrd/initramfs/ramdisk docs:
- fix typos/spellos/grammar
- clarify RAM disk config location
- correct cpio option

Acked-by: Bryan O'Sullivan <bos@serpentine.com>
Acked-by: Rob Landley <rob@landley.net>
Cc: Werner Almesberger <werner@almesberger.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/ramdisk.txt b/Documentation/ramdisk.txt
index 52f75b7..33e987d 100644
--- a/Documentation/ramdisk.txt
+++ b/Documentation/ramdisk.txt
@@ -22,16 +22,21 @@
 RAM from the buffer cache. The driver marks the buffers it is using as dirty
 so that the VM subsystem does not try to reclaim them later.
 
-Also, the RAM disk supports up to 16 RAM disks out of the box, and can
-be reconfigured to support up to 255 RAM disks - change "#define NUM_RAMDISKS"
-in drivers/block/rd.c.  To use RAM disk support with your system, run
-'./MAKEDEV ram' from the /dev directory.  RAM disks are all major number 1, and
-start with minor number 0 for /dev/ram0, etc.  If used, modern kernels use
-/dev/ram0 for an initrd.
+The RAM disk supports up to 16 RAM disks by default, and can be reconfigured
+to support an unlimited number of RAM disks (at your own risk).  Just change
+the configuration symbol BLK_DEV_RAM_COUNT in the Block drivers config menu
+and (re)build the kernel.
+
+To use RAM disk support with your system, run './MAKEDEV ram' from the /dev
+directory.  RAM disks are all major number 1, and start with minor number 0
+for /dev/ram0, etc.  If used, modern kernels use /dev/ram0 for an initrd.
 
 The old "ramdisk=<ram_size>" has been changed to "ramdisk_size=<ram_size>" to
 make it clearer.  The original "ramdisk=<ram_size>" has been kept around for
 compatibility reasons, but it may be removed in the future.
+There are also config symbols (in the Block drivers config menu) for these
+variables:  BLK_DEV_RAM_SIZE defaults to 4096 and BLK_DEV_RAM_BLOCKSIZE
+defaults to 1024.
 
 The new RAM disk also has the ability to load compressed RAM disk images,
 allowing one to squeeze more programs onto an average installation or