Add 'Sign Your Work' section [skip ci] (#710)

* Add 'Sign Your Work' section

Signed-off-by: wslulciuc <[email protected]>

CONTRIBUTING.md

@@ -6,7 +6,7 @@ We're excited you're interested in contributing to Marquez! We'd love your help,
 * Fix or improve documentation
 * Pick up a ["good first issue"](https://github.com/MarquezProject/marquez/labels/good%20first%20issue), then send a pull request our way
 
-We feel that a welcoming community is important and we ask that you follow the [Contributor Covenant Code of Conduct](CODE_OF_CONDUCT.md) in all interactions with the community.
+We feel that a welcoming community is important and we ask that you follow the [Contributor Covenant Code of Conduct](CODE_OF_CONDUCT.md) in all interactions with the community.
 
 # Development
 
@@ -47,10 +47,11 @@ $ ./gradlew spotlessApply
 3. Create a new [branch](#branching): `git checkout -b feature/my-cool-new-feature`
 4. Make change on your cool new branch
 5. Write a test for your change
-6. Make sure `.java` files are formatted: `./gradlew spotlessJavaCheck`
-7. Push change to your fork and [submit a pull request](https://github.com/MarquezProject/marquez/compare)
-8. Work with project maintainers to get your change reviewed and merged into the `master` branch
-9. Delete your branch
+6. Make sure `.java` files are formatted: `./gradlew spotlessJavaCheck`
+7. Make sure to [_sign you work_](#sign-your-work)
+8. Push change to your fork and [submit a pull request](https://github.com/MarquezProject/marquez/compare)
+9. Work with project maintainers to get your change reviewed and merged into the `master` branch
+10. Delete your branch
 
 To ensure your pull request is accepted, follow these guidelines:
 
@@ -85,6 +86,22 @@ To ensure your pull request is accepted, follow these guidelines:
 * Choose _short_ and _descriptive_ branch names
 * Use dashes (`-`) to separate _words_ in branch names
 * Use _lowercase_ in branch names
+
+# Sign Your Work
+
+The _sign-off_ is a simple line at the end of the message for a commit. All commits needs to be signed. Your signature certifies that you wrote the patch or otherwise have the right to contribute the material (see [Developer Certificate of Origin](https://developercertificate.org)):
+
+```
+This is my commit message
+
+Signed-off-by: Joe Smith <[email protected]>
+```
+
+Git has a [`-s`](https://git-scm.com/docs/git-commit#Documentation/git-commit.txt---signoff) command line option to append this automatically to your commit message:
+
+```bash
+$ git commit -s -m 'This is my commit message'
+```
 
 # API [Docs](https://github.com/MarquezProject/marquez/tree/master/docs)