I'm going to see that 0024 was the last file and add a 0025, and you while working on your feature will see the same and add a file with the same number. This will have to be noticed and resolved via renaming files during rebase and merge, etc., which is pointless busywork and easy to get wrong.
Also, I don't see why these need to be ordered sequentially at all. Surely e.g. a file like "architecture.md" or individual files like "database.md" would be better? If you change the code and that involves changing the architecture, you also update the document. You are free to include information such as why you made the change, alternatives and why they were not chosen etc., just as with this 0001-foo.md.
If you are joining a team and want to learn about the database, it's much easier to open "database.md" and find the current state, vs. reading through 0001 through 0245 where 0009 introduces why MySQL is used, 0051 explains why PostgreSQL is now being used instead of MySQL, 0121 introduces some changes, and so on. Having individual files like that is like reading Git diffs from start to finish where what you really want is the current state.