git-jump: admit to passing merge mode args to ls-files

There's even an example of such usage in the README.

Fixes: 67ba13e5a4b2 ("git-jump: pass "merge" arguments to ls-files")
Signed-off-by: Štěpán Němec <stepnem@smrk.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/contrib/git-jump/git-jump b/contrib/git-jump/git-jump
index 40c4b0d..47e0c55 100755
--- a/contrib/git-jump/git-jump
+++ b/contrib/git-jump/git-jump
@@ -9,7 +9,7 @@
 
 diff: elements are diff hunks. Arguments are given to diff.
 
-merge: elements are merge conflicts. Arguments are ignored.
+merge: elements are merge conflicts. Arguments are given to ls-files -u.
 
 grep: elements are grep hits. Arguments are given to git grep or, if
       configured, to the command in `jump.grepCmd`.