Unify naming for README and TODO comments

[yorukot]

In this project, we’ve found inconsistent naming for README files and TODO comments. According to the GNU Coding Standards, every package should include a file named README (commonly README.md), and Go projects such as golang/go follow this convention consistently. Likewise, the Go community and most IDEs recognize TODO: as the standard format for tracking future work. Variants like ReadMe.md or // todo may lead to inconsistent behavior, especially on case-sensitive systems or with static analysis tools.

To improve consistency and tooling compatibility, we should unify all README file names to README.md, and convert all TODO comments to the TODO: format. This will align our codebase with widely accepted conventions and ensure proper IDE and tool support.

Of course, the same principle applies to other common tags such as FIXME:, HACK:, and NOTE: — they should also follow consistent formatting to ensure clarity and tooling recognition across the codebase.

[yorukot]

@lazysegtree What are your thoughts?

[lazysegtree]

Yes. We should do that. No harm in sticking to a convention.