move wendelin.git to erp5.git

follow of https://lab.nexedi.com/nexedi/erp5/-/merge_requests/2138

we keep only README.md with the following content:

Wendelin

⚠️ This repository has been merged into ERP5 and is no longer maintained as a standalone project.

The full history of Wendelin has been preserved and integrated directly into the main ERP5 repository

Please go to: 👉 https://lab.nexedi.com/nexedi/erp5

for all development, issues, and contributions related to Wendelin.

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This repository remains for historical reference only.