This commit removes multiple MDX files across various directories, suggesting a significant reorganization of the documentation structure. The changes appear to be part of a broader effort to consolidate or relocate documentation content, potentially moving towards a more localized or language-specific organization (evidenced by the `en/` prefix in some file paths).

Key changes include:
- Removed files from root and subdirectories
- Updated `docs.json` to reflect new file paths
- Removed multiple concept, quickstart, and tutorial documentation files

…tructure