[dco] updated readme to include contributing/developing, calling out the dco process
[Engineering Wiki](https://github.com/sensu/engineering/wiki)
+## Contributing/Development
+
+To make a good faith effort to ensure the criteria of the MIT License are met, Sensu Inc requires the Developer Certificate of Origin (DCO) process to be followed.
+
+The DCO is an attestation attached to every contribution made by every developer. In the commit message of the contribution, the developer simply adds a Signed-off-by statement and thereby agrees to the DCO, which you can find below or at http://developercertificate.org/.
+
+```
+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.
+```
+
+The general development process is:
+
+1. Fork this repo and clone it to your workstation.
+2. Create a feature branch for your change.
+3. Write code and tests.
+4. Push your feature branch to github and open a pull request against master.
+
+
## Protobuf
### Overview
