Add template for integration test description.

[ClemensLinnhoff]

Reference to a related issue in the repository

56

Add a description Add readme template for describing integration test.

Take this checklist as orientation for yourself, if this PR is ready for Maintainer Review

• [x] My suggestion follows the governance rules.
• [x] All commits of this PR are signed.
• [x] My changes generate no errors when passing CI tests.
• [x] I updated all documentation (readmes incl. figures) according to my changes.
• [x] I have successfully implemented and tested my fix/feature locally.
• [x] Appropriate reviewer(s) are assigned.

[ClemensLinnhoff]

Waiting for https://github.com/openMSL/.github/pull/18 to be merged.

[jdsika]

Waiting for openMSL/.github#18 to be merged.

done