added best practice section in the security guidelines

SECURITY.md

@@ -1,5 +1,15 @@
 # Security Policy
 
+## Best practices
+
+If you need to fork this repository, or propose changes through pull request, be sure to not commit any sensitive informations.
+
+These informations can the the following form, without being an exhaustive list:
+
+- Credentials files (`.aws/credentials`, `.npmrc`, ...)
+- Environment variables (`JWT_SECRET`, `DATABASE_PASSWORD`, ...)
+- Personal informations (name, address, email, ...)
+
 ## Reporting a Vulnerability
 
 You just found a vulnerability in this repository and want to contribute to a safer environment.