Document legal requirements for contributing to this project

In order to contribute to this project, you need to agree to the DCO.
Before this change, there was no good way for someone to know that they
needed to agree to the DCO before they started contributing. New
contributors would be told that they need to agree to the DCO by the
Developer Certificate of Origin GitHub App [1], but that doesn’t happen
until after a new contributor has submitted their pull request.

[1]: <https://probot.github.io/apps/dco>

Signed-off-by: Jason Yundt <jason@jasonyundt.email>

Author: Jayman2000

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