added DCO (#764)

Signed-off-by: Philip Molares <philip.molares@udo.edu>

.github/pull_request_template.md

@@ -6,12 +6,13 @@ This PR fixes/adds/improves/...
 
 ### Steps
 
-<!-- please tick steps this PR performs (if something is not necessary, please tick anyway to indicate you considered it) -->
+<!-- Please tick all steps this PR performs (if something is not necessary, please remove it) -->
 
-- [ ] added implementation
-- [ ] added / updated tests
-- [ ] added / updated documentation
-- [ ] extended changelog
+- [ ] Added implementation
+- [ ] Added / updated tests
+- [ ] Added / updated documentation
+- [ ] Extended changelog
+- [ ] I read the [contribution documentation](https://github.com/hedgedoc/react-client/blob/master/CONTRIBUTING.md) and signed-off my commits to accept the DCO.
 
 ### Related Issue(s)
 <!-- e.g #123 -->

CONTRIBUTING.md

@@ -30,6 +30,26 @@ HedgeDoc is a volunteer effort. We encourage you to pitch in and to help us maki
 
 Thanks! :heart: :heart: :heart:
 
+## Certificate of Origin
+
+By contributing to this project you agree to the [Developer Certificate of
+Origin (DCO)](developer-certificate-of-origin.txt). 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.
+The DCO is a legally binding statement, please [read it carefully](developer-certificate-of-origin.txt).
+
+If you can certify it, then just add a line to every git commit message:
+
+```
+  Signed-off-by: Jane Doe <jane.doe@example.org>
+```
+
+Use your real name (sorry, no pseudonyms or anonymous contributions).
+
+If you set your `user.name` and `user.email` git configs, you can sign your commit automatically with `git commit -s`.
+You can also use git [aliases](https://git-scm.com/book/tr/v2/Git-Basics-Git-Aliases) like `git config --global alias.ci 'commit -s'`.
+Now you can commit with `git ci` and the commit will be signed.
+
 [issues]: https://github.com/codimd/react-client/issues
 [new_issue]: https://github.com/codimd/react-client/issues/new/choose
 [matrix-support]: https://matrix.to/#/#hedgedoc:matrix.org

developer-certificate-of-origin.txt

@@ -0,0 +1,35 @@
+Developer Certificate of Origin
+Version 1.1
+
+Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
+660 York Street, Suite 102,
+San Francisco, CA 94110 USA
+
+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.