Add DCO

DCO

@@ -0,0 +1,34 @@
+Developer Certificate of Origin
+Version 1.1
+
+Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
+
+Everyone is permitted to copy and distribute verbatim copies of this
+license document, but changing it is not allowed.
+
+
+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.

README.md

@@ -93,7 +93,19 @@ For more information about the OLDI Seed dataset, please see [oldi.org](https://
 
 ## Contributing
 
-Fixes and new language contributions are most welcome. Please see the [Contribution guidelines](https://oldi.org/guidelines) for further information.
+Fixes and new language contributions are most welcome.
+
+By contributing to this project you agree to the [Developer Certificate of
+Origin (DCO)](DCO). This document was created by the Linux Kernel community and is a
+simple statement that you, as a contributor, have the legal right to make the
+contribution.
+
+In order to show your agreement with the DCO you should include at the end of commit message,
+the following line: `Signed-off-by: John Doe <[email protected]>`, using your real name.
+
+This can be done easily using the `-s` flag on the `git commit`.
+
+Please see the [Contribution guidelines](https://oldi.org/guidelines) for further information.
 
 ## Changelog