doc: fix broken references

There are numerous broken references to Documentation files (in other
Documentation files, in comments, etc.). These broken references are
caused by typo's in the references, and by renames or removals of the
Documentation files. Some broken references are simply odd.

Fix these broken references, sometimes by dropping the irrelevant text
they were part of.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Documentation/filesystems/vfs.txt

@@ -1053,9 +1053,6 @@ manipulate dentries:
 	and the dentry is returned. The caller must use dput()
 	to free the dentry when it finishes using it.
 
-For further information on dentry locking, please refer to the document
-Documentation/filesystems/dentry-locking.txt.
-
 Mount Options
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