Document legal requirements for contributing to this project

CONTRIBUTING.md

@@ -0,0 +1,24 @@
+Contributing to efivar
+======================
+
+You can help us improve efivar by submitting [GitHub pull requests]. Before you
+start working on a pull request, please take a moment to review these two
+documents:
+
+* The GNU Lesser General Public License, Version 2.1. Your contributions will be
+  made available under this license when you submit a pull request.
+
+  A copy of this license can be found in [`./COPYING`].
+
+* The Developer Certificate of Origin, Version 1.1. In order for your pull
+  request to be accepted, you must indicate that you agree to this document by
+  adding a `Signed-off-by` trailer to each of the commit messages that are in
+  your pull request. Git will automatically add a `Signed-off-by` trailer for
+  you if you run [`git commit --signoff`].
+
+  A copy of this document can be found in [`./DCO`].
+
+[GitHub pull requests]: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/about-pull-requests
+[`./COPYING`]: ./COPYING
+[`git commit --signoff`]: https://git-scm.com/docs/git-commit#Documentation/git-commit.txt---signoff
+[`./DCO`]: ./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

@@ -27,3 +27,11 @@ WARNING
 You should probably not run "make a brick" *ever*, unless you're already
 reasonably sure it won't permanently corrupt your firmware.  This is not a
 joke.
+
+Contributing
+============
+
+If you would like to contribute code to the efivar project, then please take a
+look at [`./CONTRIBUTING.md`].
+
+[`./CONTRIBUTING.md`]: ./CONTRIBUTING.md