Added Code of Conduct, updated PR template with DCO.

Author: kgodey

.github/pull_request_template.md

@@ -1,11 +1,52 @@
+<!-- Add a description of the pull request underneath this line. -->
+
+<!-- If your pull request addresses an existing GitHub issue, replace the XX below with the issue number. -->
+
+Closes #XX
+
 <!-- Please follow this checklist and put an x in each of the boxes, like this: [x]. It will ensure that our team takes your pull request seriously. -->
 
+**Checklist**  
 - [ ] My pull request has a descriptive title (not a vague title like `Update index.md`)
 - [ ] My pull request targets the `master` branch of creativecommons.github.io-source.
 - [ ] I tried building the site using Lektor locally and verified that there are no build errors.
 
-<!-- If your pull request closes a GitHub issue, replace the XXXXX below with the issue number. -->
+<!-- Make sure you read and understand the following attestation. -->
+
+Developer Certificate of Origin
+Version 1.1
+
+Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
+1 Letterman Drive
+Suite D4700
+San Francisco, CA, 94129
+
+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
 
-Closes #XXXXX
+(c) The contribution was provided directly to me by some other
+    person who certified (a), (b) or (c) and I have not modified
+    it.
 
-<!-- You may add your description of the pull request underneath this line. -->
+(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.

CODE_OF_CONDUCT.md

@@ -0,0 +1,7 @@
+# Contributor Code of Conduct
+
+The Creative Commons team is committed to fostering a welcoming community.
+
+**Our Code of Conduct can be found here**: [https://creativecommons.github.io/community/code-of-conduct/](https://creativecommons.github.io/community/code-of-conduct/)
+
+For a history of updates, see the [page history here](https://github.com/creativecommons/creativecommons.github.io-source/commits/master/content/community/code-of-conduct/contents.lr).