update contributing guide

CONTRIBUTING.md

@@ -4,6 +4,7 @@
 
 - [Contributing guidelines](#contributing-guidelines)
     - [Contributions](#contributions)
+    - [Certificate of Origin](#certificate-of-origin)
     - [Contributing A Patch](#contributing-a-patch)
     - [Issue and Pull Request Management](#issue-and-pull-request-management)
     - [Pre-check before submitting a PR](#pre-check-before-submitting-a-pr)
@@ -17,6 +18,13 @@
 
 All contributions to the repository must be submitted under the terms of the [Apache Public License 2.0](https://www.apache.org/licenses/LICENSE-2.0).
 
+## Certificate of Origin
+
+By contributing to this project you agree to the Developer Certificate of
+Origin (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. See the [DCO](DCO) file for details.
+
 ## Contributing A Patch
 
 1. Submit an issue describing your proposed change to the repo in question.
@@ -51,4 +59,4 @@ export BUILD_LOCALLY=1
 make
 ```
 
-Now, you can follow the [getting started guide](./README.md#getting-started) to work with the ACM Foundation.
+Now, you can follow the [getting started guide](./README.md#getting-started) to work with this repository.

DCO

@@ -0,0 +1,37 @@
+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
+
+(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.