doc: stabilize subpath patterns

PR-URL: #36177
Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

doc/api/packages.md

@@ -323,8 +323,6 @@ analogous to the exports field.
 
 ### Subpath patterns
 
-> Stability: 1 - Experimental
-
 For packages with a small number of exports or imports, we recommend
 explicitly listing each exports subpath entry. But for packages that have
 large numbers of subpaths, this might cause `package.json` bloat and