docs: add signed commits documentation

Signed-off-by: Salim Afiune Maya <[email protected]>

DEVELOPER_GUIDELINES.md

@@ -1,11 +1,16 @@
-## Go-sdk Developer Guidelines
+## Developer Guidelines
+
+## Signed Commits
+Signed commits are required for any contribution to this project. Please see Github's documentation on configuring signed commits, [tell git about your signing key](https://docs.github.com/en/github/authenticating-to-github/managing-commit-signature-verification/telling-git-about-your-signing-key) and [signing commits](https://docs.github.com/en/authentication/managing-commit-signature-verification/signing-commits)
 
 ## Commit message standard
 
 The format is:
 ```
 type(scope): subject
+
 BODY
+
 FOOTER
 ```
 
@@ -50,4 +55,4 @@ The body should contain a longer description of the change, try not to repeat th
 Put as much context as you think it is needed, don’t be shy and explain your thought process, limitations, ideas for new features or fixes, etc.
 
 ### Footer
-The footer is used to reference issues, pull requests or breaking changes, for example, “Fixes ticket #123”.
+The footer is used to reference issues, pull requests or breaking changes, for example, “Fixes ticket #123”.