feat(doc): update priority tags configuration guide wiki

docs/priority_tags_help.md

@@ -25,6 +25,25 @@ Each entry is separated by a comma, in order from highest to lowest priority:
 
 Aliases live inside `()` and are separated with `|`. The canonical name is what appears in folder names and UI suggestions when any of the aliases are detected. Matching is case-insensitive.
 
+## Use `{first_tag}` in Path Templates
+
+When your path template contains `{first_tag}`, the app picks a folder name based on your priority list and the model’s own tags:
+
+- It checks the priority list from top to bottom. If a canonical tag or any of its aliases appear in the model tags, that canonical name becomes the folder name.
+- If no priority tags are found but the model has tags, the very first model tag is used.
+- If the model has no tags at all, the folder falls back to `no tags`.
+
+### Example
+
+With a template like `/{model_type}/{first_tag}` and the priority entry list `character(char|chars), style(anime|toon)`:
+
+| Model Tags | Folder Name | Why |
+| --- | --- | --- |
+| `["chars", "female"]` | `character` | `chars` matches the `character` alias, so the canonical wins. |
+| `["anime", "portrait"]` | `style` | `anime` hits the `style` entry, so its canonical label is used. |
+| `["portrait", "bw"]` | `portrait` | No priority match, so the first model tag is used. |
+| `[]` | `no tags` | Nothing to match, so the fallback is applied. |
+
 ## 3. Save the Settings
 
 After editing the entry list, press **Enter** to save. Use **Shift+Enter** whenever you need a new line. Clicking outside the field also saves automatically. A success toast confirms the update.