Fix production-deployment README.md

[MosbyTheGreat]

The EDC_OAUTH_CLIENT_ID should not be the SKI/AKI, but instead the same as MY_EDC_PARTICIPANT_ID.

This PR fixes the question in the according README.md

Checklist

• The PR title is short and expressive.
• I have updated the CHANGELOG.md. Hints on formulation: Important information first, details second.
• I have performed a self-review
• I understand that my contributions will be contributed under the Contributor License Agreement (CLA) which has to be agreed to on your first contribution.

[CLAassistant]

All committers have signed the CLA.

[ghost]

Hello and thank you for your contribution 🚀 I will forward it internally to decide how to proceed

[ghost]

Hello, I will forward this internally, but the EDC_OAUTH_CLIENT_ID depends on the respective data space and how it is configured and setup. Some use older ski-aki, others IDs such as BPN or MDS-ID etc. As long as everyone within a data space follows the same schema after agreeing on an specific ID everything could actually be valid.

Here's a ping to the experts in this field: @richardtreier @ununhexium