docs(contributing): update pull request guidelines and clarify branch roles

CONTRIBUTING.md

@@ -153,7 +153,7 @@ curl -sSL "https://github.com/buildpacks/pack/releases/download/v0.35.0/pack-v0.
 
 ## Pull Request
 
-- The `main` branch is the source of truth and should always reflect the latest stable release.
+- The `canary` branch is the source of truth and should always reflect the latest stable release.
 - Create a new branch for each feature or bug fix.
 - Make sure to add tests for your changes.
 - Make sure to update the documentation for any changes Go to the [docs.dokploy.com](https://docs.dokploy.com) website to see the changes.
@@ -162,6 +162,12 @@ curl -sSL "https://github.com/buildpacks/pack/releases/download/v0.35.0/pack-v0.
 - If your pull request fixes an open issue, please reference the issue in the pull request description.
 - Once your pull request is merged, you will be automatically added as a contributor to the project.
 
+**Important Considerations for Pull Requests:**
+
+- **Focus and Scope:** Each Pull Request should ideally address a single, well-defined problem or introduce one new feature. This greatly facilitates review and reduces the chances of introducing unintended side effects.
+- **Avoid Unfocused Changes:** Please avoid submitting Pull Requests that contain only minor changes such as whitespace adjustments, IDE-generated formatting, or removal of unused variables, unless these are part of a larger, clearly defined refactor or a dedicated "cleanup" Pull Request that addresses a specific `good first issue` or maintenance task.
+- **Issue Association:** For any significant change, it's highly recommended to open an issue first to discuss the proposed solution with the community and maintainers. This ensures alignment and avoids duplicated effort. If your PR resolves an existing issue, please link it in the description (e.g., `Fixes #123`, `Closes #456`).
+
 Thank you for your contribution!
 
 ## Templates