Added DCO sign-off guidance for contributing to Dapr

Signed-off-by: Nick Greenfield <nigreenf@microsoft.com>
Signed-off-by: Antonio Robson de Paula <robson.p@sidi.org.br>

daprdocs/content/en/contributing/contributing-overview.md

@@ -54,8 +54,48 @@ All contributions come through pull requests. To submit a proposed change, follo
     - Code changes require tests
 1. Update relevant documentation for the change
 1. Commit and open a PR
-1. Wait for the CI process to finish and make sure all checks are green
-1. A maintainer of the project will be assigned, and you can expect a review within a few days
+
+    - Developer Certificate of Origin: Signing your work
+    
+        The Developer Certificate of Origin (DCO) is a lightweight way for contributors to certify that they wrote or otherwise have the right to submit the code they are contributing to the project. Here is the full [text of the DCO](https://developercertificate.org/), reformatted for readability:
+        ```
+        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.
+        ```
+
+        Contributors _sign-off_ that they adhere to these requirements by adding a `Signed-off-by` line to commit messages.
+        ```bash
+        This is my commit message
+
+        Signed-off-by: Random J Developer <random@developer.example.org>
+        ```
+
+        Git even has a `-s` command line option to append this automatically to your commit message:
+
+        ```bash
+        $ git commit -s -m 'This is my commit message'
+        ```
+
+        Once commits have been signed and a PR has been open, wait for the CI process to finish and make sure all checks are green. A maintainer of the project will be assigned, and you can expect a review within a few days
+
+    - I didn't sign my commit, what do I do now?
+
+        You can easily replay your changes, sign them and force push them!
+
+        ```bash
+        git checkout <branch-name>
+        git reset $(git merge-base main <branch-name>)
+        git add -A
+        git commit -sm "one commit on <branch-name>"
+        git push --force
+        ```
 
 #### Use work-in-progress PRs for early feedback