Is it possible to save at the repository a guideline to PR reviewers?
Code review is not a simple task, there are many details to pay attention and some kind of checklist may help the process.
Example: Suppose that development create a new function and the project has some naming rules to follow. Most the reviewers worried about the code logic and forget to analyze the function name. But, with review guideline, the reviewer will not forget the naming rules anymore!
Note that it is very helpfull when a new reviewer come to the project or in case of complex PRs where some littles basics details may be forgotten, as function names for example.