[VC Security & Trust Document] term trust framework should be defined

[Macke]

Imported from AB/Connect bitbucket: https://bitbucket.org/openid/connect/issues/2006

Original Reporter: danielfett

By Kristina:

term trust framework should be defined.

for example, the examples in the following sentenceThe Verifier decides, based on policy, regulation, conformity assessment, and/or contracts, to trust a certain Issuer... are paraphrased as a “trust framework“. while other occurrences say By convention, specification or trust framework