docs: clarify preset file name recommendations (#28443)

Co-authored-by: Michael Kriese <michael.kriese@visualon.de>

docs/usage/config-presets.md

@@ -10,15 +10,6 @@ Read the [Key concepts, presets](./key-concepts/presets.md) page to learn more a
 
 Shareable config presets must use the JSON or JSON5 formats, other formats are not supported.
 
-<!-- prettier-ignore -->
-!!! warning
-    Only use `default.json` for your presets.
-
-<!-- prettier-ignore -->
-!!! warning
-    We've deprecated using a `renovate.json` file for presets, as this causes issues if the repository configuration _also_ uses a `renovate.json` file.
-    If you're using a `renovate.json` file to share your presets, rename it to `default.json`.
-
 <!-- prettier-ignore -->
 !!! tip
     Describe what your preset does in the `"description"` field.
@@ -42,6 +33,17 @@ Alternatively, Renovate can fetch preset files from an HTTP server.
 
 You can set a Git tag (like a SemVer) to use a specific release of your shared config.
 
+### Preset File Naming
+
+Presets are repo-hosted, and you can have one or more presets hosted per repository.
+If you omit a file name from your preset (e.g. `github>abc/foo`) then Renovate will look for a `default.json` file in the repo.
+If you wish to have an alternative file name, you need to specify it (e.g. `github>abc/foo//alternative-name.json5`).
+
+<!-- prettier-ignore -->
+!!! warning
+    We've deprecated using a `renovate.json` file for the default _preset_ file name in a repository.
+    If you're using a `renovate.json` file to share your presets, rename it to `default.json`.
+
 ### GitHub
 
 | name                                        | example use                      | preset    | resolves as                  | filename        | Git tag        |