Remove line limit of where you can add review comments in pull requests

When commenting on a PR, it is only possible to add comments closer than  10 lines to actual changes.

This arbitrary limitation is pointless; it should be possible to add comments anywhere.

e.g. if a change is not fully completed, and a change is needed to be added to a line more than 10 lines away, it is not possible to point to the exact location, and one have to explain it in a file comment. So this limitation actually hinders doing easy PR commenting.

p.s. if it is not pointless, can you please explain the reason for having this limit, and why it is 10?