Ensure TAP references do not have TUF specific content

[mnm678]

As discussed in the 3/13 standards meeting, we need to ensure that any referenced TAPs have consistent TUF/Uptane terminology.

[mnm678]

I went through TAP 3, 4, and 5 to look for inconsistencies with Uptane terminology. Other than a couple of TUF examples, I think these TAPs are consistent with Uptane. There are a couple of very minor TUF/Uptane differences that come up in the TAPs (for example whether to verify custom metadata), but the terminology all seems to be consistent.

Overall I would say the references to these TAPs make sense in the context of Uptane, and I don’t see a reason to duplicate them.

I am going to close this issue, but if anyone has objections I’m happy to reopen it for more discussion.