chore: update & simplify supported releases.

Author: rektide

README.md

@@ -89,11 +89,9 @@ Restify aims to support the Node.js LTS (Active and Maintenance) versions along
 
 | Node Release | Supported in Current Version | Notes |
 | :--: | :---:   | :---: |
-| 18.x | **No**  | Current stable. See [#1888](https://github.com/restify/node-restify/issues/1888) |
-| 16.x | **Yes** | Active LTS |
-| 14.x | **Yes** | Maintenance LTS |
-| 12.x | **No**  | Use restify v8.x, team will backport critical issues only |
-| 12.x | **No**  | Use restify v8.x, team will backport critical issues only |
+| 18.x | **Yes**  | Restify v10.x required. |
+| 16.x | **Yes** | |
+| 14.x | **Yes** | |
 
 ## License