Bug: Routes - missing (:id)

[TimBrownlaw]

Describe the bug
The current user guide relating to routes, still has references to the placeholder (:id) in examples.

CodeIgniter 4 version
Codeigntier 4.0.2

Affected module(s)
/system/Router/RouteCollection.php or the userguide

Expected behavior, and steps to reproduce if appropriate
Depending upon what has been decided in regards to this, either

1. Any references to (:id) in the current user guide should be altered to (:num) or
2. It should be added to $placeholder. It looks like it's been deprecated as would be expected.

I noticed that (:num) is the same as the "old" (:id) so it might just be a case of replacing (:id) with (:num) in the documentation.