fsck docs: remove outdated and useless diagnostic

In git-fsck(1), there was a reference to the warning "<tree> has full
pathnames in it".  This exact wording has not been used since 2005
(commit f1f0d08), when the wording was changed slightly.  More
importantly, the description of that warning was useless, and there were
many other similar warning messages which were not document at all.
Since all these warnings are fairly obvious, there is no need for them
to be in the man page.

Signed-off-by: Mark Lodato <lodatom@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-fsck.txt

@@ -123,9 +123,6 @@ dangling <type> <object>::
 	The <type> object <object>, is present in the database but never
 	'directly' used. A dangling commit could be a root node.
 
-warning: git-fsck: tree <tree> has full pathnames in it::
-	And it shouldn't...
-
 sha1 mismatch <object>::
 	The database has an object who's sha1 doesn't match the
 	database value.