Adding guidelines to the table of content

Signed-off-by: Martin Gaievski <[email protected]>

DEVELOPER_GUIDE.md

@@ -17,6 +17,7 @@
   - [Supported configurations](#supported-configurations)
   - [Submitting Changes](#submitting-changes)
   - [Building On Lucene Version Updates](#building-on-lucene-version-updates)
+  - [Code Guidelines](#code-guidelines)
 
 # Developer Guide
 
@@ -403,6 +404,9 @@ mocking is impractical. Include one or two unhappy paths to confirm that correct
 Whenever possible, favor scenarios that do not require model deployment. If model deployment is necessary, use an existing 
 model, as tests involving new model deployments are the most resource-intensive.
 
+If your changes could affect backward compatibility, please include relevant backward compatibility tests along with your 
+PR. For guidance on adding these tests, refer to the [Backwards Compatibility Testing](#backwards-compatibility-testing) section in this guide.
+
 ### Outdated or irrelevant code
 
 Do not submit code that is not used or needed, even if it's commented. We rely on github as version control system, code