docs: sub category

Signed-off-by: Egor Berezovskiy <[email protected]>

Author: Wadjetz

content/docs/reference/design-docs/subcategory/index.en.md

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+---
+title: "Sub category"
+linkTitle: "Sub category"
+weight: 60
+description: "Describes the sub-category model and its relation to train schedules and paced trains."
+---
+
+## Introduction
+
+Sub categories are created via a dedicated API. Each sub category has a name and a unique code, as well as visual properties like **color**, **hovered_color**, and **background_color**.
+Each sub category is associated with a parent main category.
+Both **TrainSchedules** and **PacedTrains** can specify either a **main_category** or a user-defined **sub_category**.
+
+### SubCategory model
+
+```yml
+name: "RER"
+code: "RER"
+main_category: "COMMUTER_TRAIN"
+color: "#FF0000"
+hovered_color: "#FFA500"
+background_color: "#FFD700"
+```
+
+### Train Schedule & Paced Train Category
+
+The category field in train schedules and paced trains can take either:
+
+```yml
+category:
+  main_category: "COMMUTER_TRAIN"
+```
+
+Or
+
+```yml
+category:
+  sub_category_code: "RER"
+```
+
+Only one of the two can be defined at a time, or both can be absent.
+
+If a referenced sub category is deleted, the affected train schedules or paced trains will automatically fall back to the sub category’s associated **main_category**.
+
+## Sub categories Api
+
+### Create sub categories
+
+Creates one or more sub categories in batch.
+
+```
+POST /api/sub_category
+```
+
+Request body: array of sub category objects.
+
+### Retrieve sub categories
+
+Retrieves paginated sub categories.
+
+```
+GET /api/sub_category?page=1&page_size=1000
+```
+
+### Delete sub categories
+
+Deletes a sub category using its code.
+
+```
+DELETE /sub_category/:code
+```

content/docs/reference/design-docs/subcategory/index.fr.md

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+---
+title: "Sub category"
+linkTitle: "Sub category"
+weight: 60
+description: "Décrit le modèle de sous-catégorie et sa relation avec train schedules et paced trains."
+---
+
+_Non traduit : veuillez sélectionner une autre langue._