docs: path-lookup: Add macro name to symlink limit description

Add macro name MAXSYMLINKS to the symlink limit description, so
that it is consistent with path name length description above.
Signed-off-by: Fox Chen <foxhlchen@gmail.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20210527091618.287093-7-foxhlchen@gmail.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/path-lookup.rst

@@ -992,8 +992,8 @@ is 4096.  There are a number of reasons for this limit; not letting the
 kernel spend too much time on just one path is one of them.  With
 symbolic links you can effectively generate much longer paths so some
 sort of limit is needed for the same reason.  Linux imposes a limit of
-at most 40 symlinks in any one path lookup.  It previously imposed a
-further limit of eight on the maximum depth of recursion, but that was
+at most 40 (MAXSYMLINKS) symlinks in any one path lookup.  It previously imposed
+a further limit of eight on the maximum depth of recursion, but that was
 raised to 40 when a separate stack was implemented, so there is now
 just the one limit.