* docs: add directory depth limitation warning to custom components
Add a warning admonition to the custom components documentation
explaining the MAX_DEPTH=2 limitation for component discovery.
The warning clarifies:
- Components must be at most 2 levels deep (category/component.py)
- Each first-level directory becomes an independent category in the UI
- How to modify MAX_DEPTH for advanced use cases
This addresses confusion around subdirectory support mentioned in issue #13102.
* docs: simplify directory depth warning per review feedback
Co-Authored-By: Antonio <antonio@oriontech.me>
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Co-authored-by: Antonio <antonio@oriontech.me>
