Document CSAF TC best practices for artefact linkage

There is more to TC work than issue processing: More often than not, the members need to introduce linkage / name relations to perform tasks and progress work products.

Given the specific artefact naming and referencing patterns as offered by OASIS and the tools provided, we should generate and ideally agree on a documentation of best practices.

Especially care should be taken on two aspects:

• Mappings among TC-private, OASIS-private, and public references for the same entity

• Ease of use, so the conventions stand the test of time and don't get in our way.