Add missing file.

--

doc/DCO

@@ -0,0 +1,29 @@
+GnuPG Developer's Certificate of Origin.  Version 1.0
+=====================================================
+
+By making a contribution to the GnuPG 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 free software 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 free
+    software 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 free software 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 free software license(s)
+    involved.
+
+Signed-off-by: [Your name and mail address]