[PATCH] SubmittingPatches: tighten wording on "sign-off" procedure

[Junio C Hamano <gitster@pobox.com>]

The text says "if you can certify DCO then you add a Singed-off-by
trailer".  But it does not say anything about people who cannot
certify.  A natural reading may be that if you cannot certify, you
do not add the trailer, but it shouldn't hurt to be overly explicit.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

 Documentation/SubmittingPatches | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git c/Documentation/SubmittingPatches w/Documentation/SubmittingPatches
index d12094bac5..b091730771 100644
--- c/Documentation/SubmittingPatches
+++ w/Documentation/SubmittingPatches
@@ -307,35 +307,35 @@ wrote the patch or have the right to pass it on under the same license
 as ours, by "signing off" your patch.  Without sign-off, we cannot
 accept your patches.
 
-If you can certify the below D-C-O:
+If (and only if) you can certify the below D-C-O:
 
 [[dco]]
 .Developer's Certificate of Origin 1.1
 ____
 By making a contribution to this project, I certify that:

 a. The contribution was created in whole or in part by me and I
    have the right to submit it under the open source license
    indicated in the file; or

 b. The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
    license and I have the right under that license to submit that
    work with modifications, whether created in whole or in part
    by me, under the same open source license (unless I am
    permitted to submit under a different license), as indicated
    in the file; or

 c. The contribution was provided directly to me by some other
    person who certified (a), (b) or (c) and I have not modified
    it.

 d. I understand and agree that this project and the contribution
    are public and that a record of the contribution (including all
    personal information I submit with it, including my sign-off) is
    maintained indefinitely and may be redistributed consistent with
    this project or the open source license(s) involved.
 ____

 you add a "Signed-off-by" trailer to your commit, that looks like
 this: