Update CONTRIBUTING.md

Author: LesiaChaban

CONTRIBUTING.md

@@ -2,6 +2,27 @@
 
 Thank you for your interest in contributing to this repository—your efforts are highly appreciated. This document should provide you with everything you need to get started.
 
+## Contributing code
+
+Before submitting code via a pull request,
+you will need to have signed the [Oracle Contributor Agreement][OCA] (OCA) and
+your commits need to include the following line using the name and e-mail
+address you used to sign the OCA:
+
+```text
+Signed-off-by: Your Name <you@example.org>
+```
+
+This can be automatically added to pull requests by committing with `--sign-off`
+or `-s`, e.g.
+
+```text
+git commit --signoff
+```
+
+Only pull requests from committers that can be verified as having signed the OCA
+can be accepted.
+
 ## Asking Questions
 
 If you have questions regarding the extension or its API, we highly recommend posting them in the [QA][qa-link] section under the extension's home page in the marketplace.
@@ -32,12 +53,14 @@ Feature and enhancement requests are welcomed, before you file one, take time to
 - Motivation: document why do you think the feature/enhancement is needed, how will it be useful to users, ...etc.
 - Scope & goals: describe the scope and goals of the feature, and how does it align with our product's scope and goals.
 
+ If you'd like more specific guidelines, see the [Contributor Covenant Code of Conduct][cccc-link].
 ## Code of conduct
 
-Follow the [Golden Rule][golden-rule-link]. If you'd like more specific guidelines, see the [Contributor Covenant Code of Conduct][cccc-link].
+Follow the [Golden Rule](https://en.wikipedia.org/wiki/Golden_Rule). If you'd like more specific guidelines, see the [Contributor Covenant Code of Conduct][cccc-link].
 
 <!-- Links -->
 [issues-link]: https://github.com/oracle-samples/sql-developer-vscode/issues
 [qa-link]: https://marketplace.visualstudio.com/items?itemName=Oracle.sql-developer&ssr=false#qna
 [golden-rule-link]: https://en.wikipedia.org/wiki/Golden_Rule
 [cccc-link]: https://www.contributor-covenant.org/version/1/4/code-of-conduct/
+[OCA]: https://oca.opensource.oracle.com