docs: Add guidelines for reviews and prep commits.

CONTRIBUTING.md

@@ -157,6 +157,8 @@ This will open VSCode whenever you run a command that requires a text editor, li
 
 All contributions go through a code review process to ensure the quality and maintainability of the codebase. During the review, maintainers may provide feedback or request changes to your code. Please be responsive to the feedback and make the necessary updates. There may be multiple rounds of review before your changes are approved.
 
+When you open a pull request, you can request a review from the maintainers. You can also request a review after making changes in resopnse to feedback. The requested reviewer may then review the PR themselves or delegate to another maintainer.
+
 Your PR will be merged only after the maintainers approve it. Different areas of codebase are handled by different maintainers.
 
 ## Code of Conduct

CONVENTIONS.md

@@ -49,6 +49,21 @@
 
     ```
 
+### Preparatory Commits
+Preparatory commits are commits that prepare the codebase for a new feature or fix. They should not contain any functional changes. They can include things like:
+- Exporting a function from a module.
+- Renaming a variable or function.
+- Other such changes that do not affect the functionality of the code.
+
+The commit message for preparatory commits should be the same as normal commits, but the commit description should mention that it is a preparatory commit for an issue. The Fixes clause is omitted, because the commit doesn't actually fixes the issue.
+
+Example:
+```
+client: Refactor button component.
+
+This commit adds a `backgroundColor` prop to the button component to allow users to customize the background color of the button. This is in preparation to #12345.
+```
+
 ## Other Important Points
 - Use meaningful and descriptive names for variables, functions, and classes to enhance code readability.
 - Follow consistent indentation and formatting throughout the codebase (will be enforced by ESLint and prettier).