Documentation: mount_api: change kernel log wording

Change wording to say that messages are logged to the kernel log
buffer instead of to dmesg. dmesg is just one program that can
print the kernel log buffer.

Signed-off-by: Randy Dunlap <[e-mail]>
Cc: David Howells <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Alexander Viro <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/filesystems/mount_api.rst

···
      should just be set to lie inside the low-to-high range.
 
      If all is good, true is returned.  If the table is invalid, errors are
-     logged to dmesg and false is returned.
+     logged to the kernel log buffer and false is returned.
 
    * ::
 
···
 
      This performs some validation checks on a parameter description.  It
      returns true if the description is good and false if it is not.  It will
-     log errors to dmesg if validation fails.
+     log errors to the kernel log buffer if validation fails.
 
    * ::