contributing: add code review checklist

Author: ligurio

CONTRIBUTING.md

@@ -37,3 +37,32 @@ For example, for running tests in `multi`, `uuid` and `main` packages, call
 ```bash
 make test-multi test-uuid test-main
 ```
+
+## Code review checklist
+
+- Public API contains functions, variables, constants that are needed from
+  outside by users. All the rest should be left closed.
+- Public functions, variables and constants contain at least a single-line
+  comment.
+- Code is DRY (see "Do not Repeat Yourself" principle).
+- New features have functional and probably performance tests.
+- There are no changes in files not related to the issue.
+- There are no obvious flaky tests.
+- Commits with bugfixes have tests based on reproducers.
+- Changelog entry is present in `CHANGELOG.md`.
+- Public methods contain executable examples (contains a comment with
+  reference output).
+- Autogenerated documentation looks good. Run `godoc -http=:6060` and point
+  your web browser to address "http://127.0.0.1:6060" for evaluating.
+- Commit message header may start with a prefix with a short description
+  follows after colon. It is applicable to changes in a README, examples, tests
+  and CI configuration files. Examples: `github-ci: add Tarantool 2.x-latest`
+  and `readme: describe how to run tests`.
+- Check your comments, commit title, and even variable names to be
+  grammatically correct. Start sentences from a capital letter, end with a dot.
+  Everywhere - in the code, in the tests, in the commit message.
+
+See also:
+
+- https://github.com/tarantool/tarantool/wiki/Code-review-procedure
+- https://www.tarantool.io/en/doc/latest/contributing/